ESET researchers tease aside MQsTTang, a brand new backdoor utilized by Mustang Panda, which communicates by way of the MQTT protocol
ESET researchers have analyzed MQsTTang, a brand new customized backdoor that we attribute to the Mustang Panda APT group. This backdoor is a part of an ongoing marketing campaign that we will hint again to early January 2023. In contrast to a lot of the group’s malware, MQsTTang doesn’t appear to be based mostly on current households or publicly accessible tasks.
Mustang Panda is understood for its custom-made Korplug variants (additionally dubbed PlugX) and elaborate loading chains. In a departure from the group’s typical techniques, MQsTTang has solely a single stage and doesn’t use any obfuscation methods.
We now have seen unknown entities in Bulgaria and Australia in our telemetry. We even have data indicating that this marketing campaign is focusing on a governmental establishment in Taiwan. Nevertheless, because of the nature of the decoy filenames used, we imagine that political and governmental organizations in Europe and Asia are additionally being focused. This may even be in keeping with the focusing on of the group’s different latest campaigns. As documented by fellow researchers at Proofpoint, Mustang Panda has been identified to focus on European governmental entities since a minimum of 2020 and has elevated its exercise in Europe even additional, since Russia’s invasion of Ukraine. Determine 1 reveals our view of the focusing on for this marketing campaign.
We attribute this new backdoor and the marketing campaign to Mustang Panda with excessive confidence based mostly on the next indicators.
We discovered archives containing samples of MQsTTang in two GitHub repositories belonging to the consumer YanNaingOo0072022. One other GitHub repository of the identical consumer was utilized in a earlier Mustang Panda marketing campaign described by Avast in a December 2022 blogpost.
One of many servers used within the present marketing campaign was working a publicly accessible nameless FTP server that appears to be used to stage instruments and payloads. Within the /pub/god listing of this server there are a number of Korplug loaders, archives, and instruments that had been utilized in earlier Mustang Panda campaigns. This is similar listing that was utilized by the stager described within the aforementioned Avast blogpost. This server additionally had a /pub/gd listing, which was one other path utilized in that marketing campaign.
Among the infrastructure used on this marketing campaign additionally matches the community fingerprint of beforehand identified Mustang Panda servers.
MQsTTang is a barebones backdoor that enables the attacker to execute arbitrary instructions on a sufferer’s machine and get the output. Even so, it does current some attention-grabbing traits. Chief amongst these is its use of the MQTT protocol for C&C communication. MQTT is often used for communication between IoT units and controllers, and the protocol hasn’t been utilized in many publicly documented malware households. One such instance is Chrysaor, also called Pegasus for Android. From an attacker’s perspective, one in every of MQTT’s advantages is that it hides the remainder of their infrastructure behind a dealer. Thus, the compromised machine by no means communicates straight with the C&C server. As seen in Determine 2, this functionality is achieved by utilizing the open supply QMQTT library. This library is determined by the Qt framework, a big a part of which is statically linked within the malware. Utilizing the Qt framework for malware improvement can also be pretty unusual. Lazarus’s MagicRAT is likely one of the uncommon not too long ago documented examples.
MQsTTang is distributed in RAR archives which solely include a single executable. These executables often have names associated to Diplomacy and passports comparable to:
- CVs Amb Officer PASSPORT Ministry Of Overseas Affairs.exe
- Paperwork members of delegation diplomatic from Germany.Exe
- PDF_Passport and CVs of diplomatic members from Tokyo of JAPAN.eXE
- Word No.18-NG-23 from Embassy of Japan.exe
These archives are hosted on an internet server with no related area title. This reality, together with the filenames, leads us to imagine that the malware is unfold by way of spearphishing.
To this point, we’ve got solely noticed just a few samples. Moreover variations in some constants and hardcoded strings, the samples are remarkably comparable. The one notable change is the addition of some anti-analysis methods within the newest variations. The primary of those consists of utilizing the CreateToolhelp32Snapshot Home windows API operate to iterate by working processes and search for the next identified debuggers and monitoring instruments.
Word that, whereas the malware is a 32-bit executable, it solely checks for the presence of x64dbg and never its 32-bit counterpart, x32dbg.
The second approach makes use of the FindWindowW Home windows API to search for the next Window Lessons and Titles utilized by identified evaluation instruments:
- OllyDbg – [CPU]
- Immunity Debugger – [CPU]
When executed straight, the malware will launch a duplicate of itself with 1 as a command line argument. That is repeated by the brand new course of, with the argument being incremented by 1 on each run. When this argument hits particular values, sure duties might be executed. Word that the precise values fluctuate between samples; those talked about under correspond to the pattern with SHA-1 02D95E0C369B08248BFFAAC8607BBA119D83B95B. Nevertheless, the duties themselves and the order through which they’re executed is fixed.
Determine 3 reveals an summary of this conduct together with the duties which are executed when the malware is first run.
Desk 1 accommodates a listing of the duties and the worth at which every of them is executed. We’ll describe them in additional element within the upcoming paragraphs.
Desk 1. Duties executed by the backdoor
|Process quantity||Argument worth||Process description|
|1||5||Begin C&C communication.|
|2||9||Create copy and launch.|
|3||32||Create persistence copy.|
|4||119||Set up persistence.|
|5||148||Cease recursive execution.|
If any evaluation instrument or debugger is detected utilizing the methods we described beforehand, the conduct of job 1 is altered and duties 2, 3, and 4 are skipped solely.
Process 1: C&C communication
As was beforehand talked about, MQsTTang communicates with its C&C server over the MQTT protocol. All noticed samples use 126.96.36.199 as dealer. This server is a public dealer operated by EMQX, who additionally occur to be the maintainers of the QMQTT library. This might be a technique to make the community visitors appear official and to cover Mustang Panda’s personal infrastructure. Utilizing this public dealer additionally offers resiliency; the service is unlikely to be taken down due to its many official customers and, even when the present C&C servers are banned or taken down, Mustang Panda might spin up new ones and use the identical MQTT subjects with out disrupting MQsTTang’s operation.
Nevertheless, this marketing campaign may be a check case by Mustang Panda earlier than deciding whether or not to speculate the time and sources to arrange their very own dealer. That is supported by the low variety of samples we’ve noticed and the quite simple nature of MQsTTang.
As proven in Determine 4, the malware and C&C server use two MQTT subjects for his or her communication. The primary one, iot/server2, is used for communication from the shopper to the server. The second is used for communication from the server to the shopper. It follows the format iot/v2/<Distinctive ID> the place <Distinctive ID> is generated by taking the final 8 bytes, in hex kind, of a UUID. If any evaluation instrument is detected, server2 and v2 are respectively changed with server0 and v0. That is seemingly so as to keep away from tipping off defenders by solely aborting the malware’s execution early.
All communication between the server and the shopper makes use of the identical encoding scheme. The MQTT message’s payload is a JSON object with a single attribute named msg. To generate the worth of this attribute, the precise content material is first base64 encoded, then XORed with the hardcoded string nasa, and base64 encoded once more. We’ll describe the precise format of those payloads within the related sections.
Upon first connecting to the dealer, the malware subscribes to its distinctive subject. Then, and each 30 seconds thereafter, the shopper publishes a KeepAlive message to the server’s subject. The content material of this message is a JSON object with the next format:
“Alive”: “<malware’s uptime in minutes>”,
“c_topic”: “<shopper’s distinctive subject>”
When the server needs to problem a command, it publishes a message to the shopper’s distinctive subject. The plaintext content material of this message is solely the command to be executed. As proven in Determine 5, the shopper executes the obtained command utilizing QProcess::startCommand from the Qt framework. The output, obtained utilizing QProcess::readAllStandardOutput, is then despatched again in a JSON object with the next format:
“c_topic”: “<shopper’s distinctive subject>”,
“ret”: “<Command output>”
Since solely the content material of normal output is distributed again, the server is not going to obtain errors or warnings. From the server’s standpoint, a failed command is thus indistinguishable from a command that merely produces no output except some kind of redirection is carried out.
Duties 2 and three: Copying the malware
The second and third duties are pretty comparable to one another. They copy the malware’s executable to a hardcoded path; c:userspublicvdump.exe and c:userspublicvcall.exe respectively. The filenames used are totally different for every pattern, however they’re at all times positioned within the C:userspublic listing.
Within the second job, the newly created copy is then launched with the command line argument 97.
Process 4: Establishing persistence
Persistence is established by the fourth job, which creates a brand new worth qvlc set to c:userspublicvcall.exe beneath the HKCUSoftwareMicrosoftWindowsCurrentVersionRun registry key. It will trigger the malware to be executed on startup.
When MQsTTang is executed on startup as c:userspublicvcall.exe, solely the C&C communication job is executed.
The Mustang Panda marketing campaign described on this article is ongoing as of this writing. The victimology is unclear, however the decoy filenames are in keeping with the group’s different campaigns that concentrate on European political entities.
This new MQsTTang backdoor offers a type of distant shell with none of the bells and whistles related to the group’s different malware households. Nevertheless, it reveals that Mustang Panda is exploring new expertise stacks for its instruments. It stays to be seen whether or not this backdoor will turn into a recurring a part of the group’s arsenal, however it’s yet another instance of the group’s quick improvement and deployment cycle.
|A1C660D31518C8AFAA6973714DE30F3D576B68FC||CVs Amb.rar||Win32/Agent.AFBI||RAR archive used to distribute MQsTTang backdoor.|
|430C2EF474C7710345B410F49DF853BDEAFBDD78||CVs Amb Officer PASSPORT Ministry Of Overseas Affairs.exe||Win32/Agent.AFBI||MQsTTang backdoor.|
|F1A8BF83A410B99EF0E7FDF7BA02B543B9F0E66C||Paperwork.rar||Win32/Agent.AFBI||RAR archive used to distribute MQsTTang backdoor.|
|02D95E0C369B08248BFFAAC8607BBA119D83B95B||PDF_Passport and CVs of diplomatic members from Tokyo of JAPAN.eXE||Win32/Agent.AFBI||MQsTTang backdoor.|
|0EA5D10399524C189A197A847B8108AA8070F1B1||Paperwork members of delegation diplomatic from Germany.Exe||Win32/Agent.AFBI||MQsTTang backdoor.|
|982CCAF1CB84F6E44E9296C7A1DDE2CE6A09D7BB||Paperwork.rar||Win32/Agent.AFBI||RAR archive used to distribute MQsTTang backdoor.|
|740C8492DDA786E2231A46BFC422A2720DB0279A||23 from Embassy of Japan.exe||Win32/Agent.AFBI||MQsTTang backdoor.|
|AB01E099872A094DC779890171A11764DE8B4360||BoomerangLib.dll||Win32/Korplug.TH||Identified Mustang Panda Korplug loader.|
|61A2D34625706F17221C1110D36A435438BC0665||breakpad.dll||Win32/Korplug.UB||Identified Mustang Panda Korplug loader.|
|30277F3284BCEEF0ADC5E9D45B66897FA8828BFD||coreclr.dll||Win32/Agent.ADMW||Identified Mustang Panda Korplug loader.|
|BEE0B741142A9C392E05E0443AAE1FA41EF512D6||HPCustPartUI.dll||Win32/Korplug.UB||Identified Mustang Panda Korplug loader.|
|F6F3343F64536BF98DE7E287A7419352BF94EB93||HPCustPartUI.dll||Win32/Korplug.UB||Identified Mustang Panda Korplug loader.|
|F848C4F3B9D7F3FE1DB3847370F8EEFAA9BF60F1||libcef.dll||Win32/Korplug.TX||Identified Mustang Panda Korplug loader.|
|IP||Area||Internet hosting supplier||First seen||Particulars|
|188.8.131.52||dealer.emqx.io||Amazon.com, Inc.||2020-03-26||Authentic public MQTT dealer.|
|80.85.156[.]151||N/A||Chelyabinsk-Sign LLC||2023-01-05||MQsTTang supply server.|
|80.85.157[.]3||N/A||Chelyabinsk-Sign LLC||2023-01-16||MQsTTang supply server.|
|185.144.31[.]86||N/A||Abuse-C Position||2023-01-22||MQsTTang supply server.|
- https://uncooked.githubusercontent[.]com/YanNaingOo0072022/ee/primary/CVs Amb.rar
MITRE ATT&CK methods
This desk was constructed utilizing version 12 of the MITRE ATT&CK framework.
|Useful resource Growth||T1583.003||Purchase Infrastructure: Digital Non-public Server||Some servers used within the marketing campaign are on shared internet hosting.|
|T1583.004||Purchase Infrastructure: Server||Some servers used within the marketing campaign appear to be unique to Mustang Panda.|
|T1587.001||Develop Capabilities: Malware||MQsTTang is a customized backdoor, most likely developed by Mustang Panda.|
|T1588.002||Acquire Capabilities: Instrument||A number of official and open- supply instruments, together with psexec, ps, curl, and plink, had been discovered on the staging server.|
|T1608.001||Stage Capabilities: Add Malware||MQsTTang was uploaded to the online server for distribution.|
|T1608.002||Stage Capabilities: Add Instrument||A number of instruments had been uploaded to an FTP server.|
|Preliminary Entry||T1566.002||Phishing: Spearphishing Hyperlink||MQsTTang is distributed by way of spearphishing hyperlinks to a malicious file on an attacker-controlled internet server.|
|Execution||T1106||Native API||MQsTTang makes use of the QProcess class from the Qt framework to execute instructions.|
|T1204.002||Person Execution: Malicious File||MQsTTang depends on the consumer to execute the downloaded malicious file.|
|Persistence||T1547.001||Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder||MQsTTang persists by making a registry Run key.|
|Protection Evasion||T1036.004||Masquerading: Masquerade Process or Service||In most samples, the registry secret’s created with the title qvlc. This matches the title of a official executable utilized by VLC.|
|T1036.005||Masquerading: Match Authentic Identify or Location||When creating copies, MQsTTang makes use of filenames of official applications.|
|T1480||Execution Guardrails||MQsTTang checks the paths it’s executed from to find out which duties to execute.|
|T1622||Debugger Evasion||MQsTTang detects working debuggers and alters its conduct if any are discovered to be current.|
|Command and Management||T1071||Utility Layer Protocol||MQsTTang communicates with its C&C server utilizing the MQTT protocol.|
|T1102.002||Internet Service: Bidirectional Communication||MQsTTang makes use of a official public MQTT dealer.|
|T1132.001||Knowledge Encoding: Customary Encoding||The content material of the messages between the malware and server is base64 encoded.|
|T1573.001||Encrypted Channel: Symmetric Cryptography||The content material of the messages between the malware and server is encrypted utilizing a repeating XOR key.|
|Exfiltration||T1041||Exfiltration Over C2 Channel||The output of executed instructions is distributed again to the server utilizing the identical protocol.|