Cisco Talos is providing an update on its two recent reports on a new and ongoing campaign where Turla, a Russian espionage group, deployed their TinyTurla-NG (TTNG) implant. We now have new information on the entire kill chain this actor uses, including the tactics, techniques and procedures (TTPs) utilized to steal valuable information from their victims and propagate through their infected enterprises. 

• Talos’ analysis, in coordination with CERT.NGO, reveals that Turla infected multiple systems in the compromised network of a European non-governmental organization (NGO). 

• The attackers compromised the first system, established persistence and added exclusions to anti-virus products running on these endpoints as part of their preliminary post-compromise actions. 

• Turla then opened additional channels of communication via Chisel for data exfiltration and to pivot to additional accessible systems in the network.

Tracing Turla’s steps from compromise to exfiltration

Talos discovered that post-compromise activity carried out by Turla in this intrusion isn’t restricted to the sole deployment of their backdoors. Before deploying TinyTurla-NG, Turla will attempt to configure anti-virus software exclusions to evade detection of their backdoor. Once exclusions have been set up, TTNG is written to the disk, and persistence is established by creating a malicious service.

Preliminary post-compromise activity and TinyTurla-NG deployment

After gaining initial access, Turla first adds exclusions in the anti-virus software, such as Microsoft Defender, to locations they will use to host the implant on the compromised systems.

Turla then sets up the persistence of the TinyTurla-NG implants using one or more batch (BAT) files. The batch files create a service on the system to persist the TTNG DLL on the system. 

This technique is identical to that used by Turla in 2021 to achieve persistence for their TinyTurla implants. However, we’re still unsure why the actor uses two different batch files, but it seems to be an unnecessarily convoluted approach to evade detections.

In the case of TTNG, the service is created with the name “sdm” masquerading as a “System Device Manager” service. 

Batch file contents.

The creation and start of the malicious service kick starts the execution of the TinyTurla-NG implant via svchost[.]exe (Windows’ service container). TinyTurla-NG is instrumented further to conduct additional reconnaissance of directories of interest and then copy files to a temporary staging directory on the infected system, followed by subsequent exfiltration to the C2. TinyTurla-NG is also used to deploy a custom-built Chisel beacon from the open-sourced offensive framework.

Custom Chisel usage

On deployment, Chisel will set up a reverse proxy tunnel to an attacker-controlled box [T1573.002 - Encrypted Channel: Asymmetric Cryptography]. We’ve observed that the attackers leveraged the chisel connection to the initially compromised system, to pivot to other systems in the network. 

The presence of Windows Remote Management (WinRM)-based connections on the target systems indicates that chisel was likely used in conjunction with other tools, such as proxy chains and evil-winrm to establish remote sessions. WinRM is Microsoft’s implementation of the WS-Management protocol and allows Windows-based systems to exchange information and be administered using scripts or built-in utilities.

The overall infection chain is visualized below.

Turla tactics, tools and procedures flow.

Once the attackers have gained access to a new box, they will repeat their activities to create Microsoft Defender exclusions, drop the malware components, and create persistence, indicating that Turla follows a playbook that can be articulated as the following cyber kill chain.

Cyber kill chain.

Analyzing the traffic originating from Chisel revealed the tool beaconed back to its C2 server every hour.

While the infected systems were compromised as early as October 2023 and Chisel was deployed as late as December 2023, Turla operators conducted the majority of their data exfiltration using Chisel much later on Jan. 12, 2024 [T1041 - Exfiltration Over C2 Channel].

Coverage

Ways our customers can detect and block this threat are listed below.

Cisco Secure Endpoint (formerly AMP for Endpoints) is ideally suited to prevent the execution of the malware detailed in this post. Try Secure Endpoint for free here.

Cisco Secure Web Appliance web scanning prevents access to malicious websites and detects malware used in these attacks.

Cisco Secure Email (formerly Cisco Email Security) can block malicious emails sent by threat actors as part of their campaign. You can try Secure Email for free here.

Cisco Secure Firewall (formerly Next-Generation Firewall and Firepower NGFW) appliances such as Threat Defense Virtual, Adaptive Security Appliance and Meraki MX can detect malicious activity associated with this threat.

Cisco Secure Malware Analytics (Threat Grid) identifies malicious binaries and builds protection into all Cisco Secure products.

Umbrella, Cisco's secure internet gateway (SIG), blocks users from connecting to malicious domains, IPs and URLs, whether users are on or off the corporate network. Sign up for a free trial of Umbrella here.

Cisco Secure Web Appliance (formerly Web Security Appliance) automatically blocks potentially dangerous sites and tests suspicious sites before users access them.

Additional protections with context to your specific environment and threat data are available from the Firewall Management Center.

Cisco Duo provides multi-factor authentication for users to ensure only those authorized are accessing your network.

Open-source Snort Subscriber Rule Set customers can stay up to date by downloading the latest rule pack available for purchase on Snort.org.

IOCS

Hashes

267071df79927abd1e57f57106924dd8a68e1c4ed74e7b69403cdcdf6e6a453b

d6ac21a409f35a80ba9ccfe58ae1ae32883e44ecc724e4ae8289e7465ab2cf40

ad4d196b3d85d982343f32d52bffc6ebfeec7bf30553fa441fd7c3ae495075fc

13c017cb706ef869c061078048e550dba1613c0f2e8f2e409d97a1c0d9949346

b376a3a6bae73840e70b2fa3df99d881def9250b42b6b8b0458d0445ddfbc044 

Domains

hanagram[.]jpthefinetreats[.]com

caduff-sa[.]chjeepcarlease[.]com

buy-new-car[.]com

carleasingguru[.]com

IP Addresses

91[.]193[.]18[.]120

• Cisco Talos, in cooperation with CERT.NGO, has discovered new malicious components used by the Turla APT. New findings from Talos illustrate the inner workings of the command and control (C2) scripts deployed on the compromised WordPress servers utilized in the compromise we previously disclosed.
• Talos also illustrates the post-compromise activity carried out by the operators of the TinyTurla-NG (TTNG) backdoor to issue commands to the infected endpoints. We found three distinct sets of PowerShell commands issued to TTNG to enumerate, stage and exfiltrate files that the attackers found to be of interest.
• Talos has also discovered the use of another three malicious modules deployed via the initial implant, TinyTurla-NG, to maintain access, and carry out arbitrary command execution and credential harvesting.
• One of these components is a modified agent/client from Chisel, an open-sourced attack framework, used to communicate with a separate C2 server to execute arbitrary commands on the infected systems.
• Certificate analysis of the Chisel client used in this campaign indicates that another modified chisel implant has likely been created that uses a similar yet distinct certificate. This assessment is in line with Turla’s usage of multiple variants of malware families including TinyTurla-NG, TurlaPower-NG and other PowerShell-based scripts during this campaign.

Talos, in cooperation with CERT.NGO, has discovered new malicious components used by the Turla APT in the compromise we’ve previously disclosed. The continued investigation also revealed details of the inner workings of the C2 scripts including handling of incoming requests and a WebShell component that allows the operators to administer the compromised C2 servers remotely.

C2 server analysis

The command and control (C2) code is a PHP-based script that serves two purposes: It’s a handler for the TinyTurla-NG implants and web shell that the Turla operators can use to execute commands on the compromised C2 server. The C2 scripts obtained by Talos are complementary to the TinyTurla-NG (TTNG) and TurlaPower-NG implants and are meant to deliver executables and administrative commands to execute on infected systems.

On load, the PHP-based C2 script will perform multiple actions to create the file structure used to serve the TTNG backdoor. After receiving a request, the C2 script first checks if the logging directory exists, if not, it will create one. Next, the script checks for a specific COOKIE ID. If it exists and corresponds to the hardcoded value, then the C2 script will act as a web shell.

It will base64 decode the value of the $_COOKIE (not to be confused with the authentication COOKIE ID) entry and execute it on the C2 server as a command. These commands are either run using the exec(), passthru(), system(), or shell_exec() functions. It will also check if the variable specified is a resource and read its contents. Once the actions are complete, the output or resource is sent to the requestor and the PHP script will stop executing.

If there is an “id” provided in the HTTP request to the C2 server, the script will treat this as communication with an implant, such as TTNG or TurlaPower-NG. The “id” parameter is the same variable that is passed by the TTNG and TurlaPower-NG implants during communication with the C2 and creates the logging directory on the C2 server, as well. Depending on the next form value accompanying the “id”, the C2 will perform the following actions:

• "task": Write the content sent by the requestor to the “<id>/tasks.txt” file and record the requestor’s IP address and timestamp in the “<id>/_log.txt”. The contents of this file are then sent to the requestor in response to the “gettask” request. Adversaries use this mechanism to add more tasks to the list of tasks/commands that each C2 must send to their backdoor installations to execute on the infected endpoints.
• "gettask": Send the contents of the “<id>/tasks.txt” file to the infected system requesting a new command to execute on the infected endpoint.
• "result": Get the content of the HTTP(S) form and record it into the “<id>/result.txt” file. The C2 uses this mechanism to obtain and record the output of a command executed on an infected endpoint by the TTNG backdoor into a file on disk.
• "getresult": Get the contents of the “<id>/result.txt” file from the C2 server. The adversaries use this to obtain the results of a command executed on the infected endpoint without having to access the C2 server.
• "file" + "name": Save the contents of the file sent to the C2 server either in full or part to a file specified on the C2 server with the same “name” specified in the HTTP form.
• "cat_file": Read the contents of a file specified by the requestor on the C2 server and respond with the contents.
• "rm_file": Remove/delete a file specified by the requestor from the C2 server.

The HTTP form values accepted by the C2 server task, cat_file, rm_file, get_result and their corresponding operations on the C2 server indicate that these are part of an operational apparatus that allows the threat actors to feed the C2 server new commands and retrieve valuable information collected by the C2 server, from a remote location, without having to log into the C2 itself. Operationally, this is a tactic that is beneficial to the threat actors considering that all C2 servers discovered so far are websites compromised by the threat actor instead of being attacker-owned. Therefore, it would be beneficial for Turla’s operators to simply communicate over HTTPS masquerading as legitimate traffic instead of re-exploiting or accessing the servers through other means such as SSH thereby increasing their fingerprint on the compromised C2 servers.

This tactic can be visualized as:

Instrumenting TinyTurla-NG to carry out post-compromise activity

The adversaries use TinyTurla-NG to perform additional reconnaissance to enumerate files of interest on the infected endpoints and then exfiltrate these files. They issued three distinct sets of modular PowerShell commands to TTNG:

• Reconnaissance commands: Used to enumerate files in a directory specified by the operator. The directory listing is returned to the operator to select interesting files that can be exfiltrated.

PowerShell script/Command enumerates files in four locations specified by the C2 and sends the results back to it.

• Copy file commands: Base64-encoded commands/scripts issued to the infected systems to copy over files of interest from their original location to a temporary directory, usually: C:\windows\temp\

• Exfiltration commands/scripts aka TurlaPower-NG: These scripts were used to finally exfiltrate the selected files to the C2 servers.

The scripts used during enumeration, copying and exfiltration tasks contain hardcoded paths for files and folders of interest to Turla. These locations consisted of files and documents that were used and maintained by Polish NGOs to conduct their day-to-day operations. The actors also used these scripts to exfiltrate Firefox profile data, reinforcing our assessment that Turla made attempts to harvest credentials, along with data exfiltration.

While Tinyturla-NG itself is enough to perform a variety of unauthorized actions on the infected system using a combination of scripts described above, the attackers chose to deploy three more tools to aid in their malicious operations:

• Chisel: Modified copy of the Chisel client/agent.
• Credential harvesting scripts: PowerShell-based scripts for harvesting Google Chrome or Microsoft Edge’s saved login data.
• Tool for executing commands with elevated privileges: A binary that is meant to impersonate privilege levels of a specified process while executing arbitrary commands specified by the parent process.

The overall infection activity once TTNG has been deployed looks like this:

Using Chisel as another means of persistent access

Talos’ investigation uncovered that apart from TurlaPower-NG, the PowerShell-based file exfiltrator, the adversary also deployed another implant on infected systems. It’s a modified copy of the GoLang-based, open-source tunneling tool Chisel stored in the location: C:\Windows\System32\TrustedWorker[.]exe

The modified Chisel malware is UPX compressed, as is common for Go binaries, and contains the C2 URL, port and communication certificate, and private keys embedded in the malware sample. Once it decrypts these artifacts, it continues to create a reverse SOCKS proxy connection to the C2 using the configuration: R:5000:socks

In the proxy:

• “R”: Stands for remote port forwarding.
• “5000”: This is the port on the attacker machine that receives the connection from the infected system.
• “socks”: Specifies the usage of the SOCKS protocol. 

(The default local host and port for a socks remote in Chisel is 127[.]0[.]0[.]1:1080.)

The C2 server that the chisel sample contacts is: 91[.]193[.]18[.]120:443.

The TLS configuration consists of a client TLS certificate and key pair. The certificate is valid between Dec. 7, 2023 and Dec. 16, 2024. This validity falls in line with Talos’ assessment that the campaign began in December 2023. The issuer of the certificate is named “dropher[.]com” and the subject name is “blum[.]com”.

During our data analysis, we found another certificate which we assessed with high confidence was also generated by Turla operators, but it's unclear if this was a mistake or if they intended for the certificate to be used on another modified chisel implant. 

The new certificate has the same issuer but in this case, the common name is blum[.]com and the serial number is 0x1000. This certificate was generated one second before the one used in the modified chisel client/agent.

Additional tools for elevated process execution and credential harvesting

Turla also deployed two more tools to aid their malicious operations on the infected systems. One is used to run arbitrary commands on the system and the other is used to steal Microsoft Edge browser’s login data.

The first tool is a small and simple Windows executable to create a new command line process on the system by impersonating the privilege level of another existing process. The tool will accept a target Process Identifier (PID) representing the process whose privilege level is to be impersonated and the command line that needs to be executed. Then, a new cmd[.]exe is spawned and used to execute arbitrary commands on the infected endpoint. The binary was compiled in early 2022 and was likely used in previous campaigns by Turla.

The second tool discovered by Talos is a PowerShell script residing at the location:

C:\windows\system32\edgeparser.ps1

This script is used to find  login data from Microsoft Edge located at:

%userprofile%\AppData\Local\Microsoft\Edge\User Data\Default\Login Data

This data file and the corresponding decryption key for the login data extracted from the endpoint is archived into a ZIP file and stored in the directory: C:\windows\temp\<filename>.zip

The script can be used to obtain credentials for Google Chrome as well but has been modified to parse login data from:

%userprofile%\AppData\Local\Microsoft\Edge

TTNG uses the privilege elevation tool to run the PowerShell script using the command:

"C:\Windows\System32\i.exe" _PID_ "powershell -f C:\Windows\System32\edgeparser.ps1"

This results in the tool spawning a new process with the command line:

C:\Windows\System32\cmd.exe /c "powershell -f C:\Windows\System32\edgeparser.ps1"

Coverage

Ways our customers can detect and block this threat are listed below.

Cisco Secure Endpoint (formerly AMP for Endpoints) is ideally suited to prevent the execution of the malware detailed in this post. Try Secure Endpoint for free here.

Cisco Secure Web Appliance web scanning prevents access to malicious websites and detects malware used in these attacks.

Cisco Secure Email (formerly Cisco Email Security) can block malicious emails sent by threat actors as part of their campaign. You can try Secure Email for free here.

Cisco Secure Firewall (formerly Next-Generation Firewall and Firepower NGFW) appliances such as Threat Defense Virtual, Adaptive Security Appliance and Meraki MX can detect malicious activity associated with this threat.

Cisco Secure Malware Analytics (Threat Grid) identifies malicious binaries and builds protection into all Cisco Secure products.

Umbrella, Cisco's secure internet gateway (SIG), blocks users from connecting to malicious domains, IPs and URLs, whether users are on or off the corporate network. Sign up for a free trial of Umbrella here.

Cisco Secure Web Appliance (formerly Web Security Appliance) automatically blocks potentially dangerous sites and tests suspicious sites before users access them.

Additional protections with context to your specific environment and threat data are available from the Firewall Management Center.

Cisco Duo provides multi-factor authentication for users to ensure only those authorized are accessing your network.

Open-source Snort Subscriber Rule Set customers can stay up to date by downloading the latest rule pack available for purchase on Snort.org.

IOCs

IOCs for this research can also be found in our GitHub repository here.

Hashes

267071df79927abd1e57f57106924dd8a68e1c4ed74e7b69403cdcdf6e6a453b
d6ac21a409f35a80ba9ccfe58ae1ae32883e44ecc724e4ae8289e7465ab2cf40
ad4d196b3d85d982343f32d52bffc6ebfeec7bf30553fa441fd7c3ae495075fc
13c017cb706ef869c061078048e550dba1613c0f2e8f2e409d97a1c0d9949346
b376a3a6bae73840e70b2fa3df99d881def9250b42b6b8b0458d0445ddfbc044

Domains

hanagram[.]jp
thefinetreats[.]com
caduff-sa[.]ch
jeepcarlease[.]com
buy-new-car[.]com
carleasingguru[.]com

IP Addresses

91[.]193[.]18[.]120

• Cisco Talos has identified a new backdoor authored and operated by the Turla APT group, a Russian cyber espionage threat group. This new backdoor we’re calling “TinyTurla-NG” (TTNG) is similar to Turla’s previously disclosed implant, TinyTurla, in coding style and functionality implementation.
• Talos assesses with high confidence that TinyTurla-NG, just like TinyTurla, is a small “last chance” backdoor that is left behind to be used when all other unauthorized access/backdoor mechanisms have failed or been detected on the infected systems.
• TinyTurla-NG was seen as early as December 2023 targeting a Polish non-governmental organization (NGO) working on improving Polish democracy and supporting Ukraine during the Russian invasion. 
• We’ve also discovered previously unknown PowerShell scripts we’re calling “TurlaPower-NG '' that are meant to act as file exfiltrators. TinyTurla-NG deployed these scripts to exfiltrate key material used to secure the password databases of popular password management software, indicating a concerted effort for Turla to steal login credentials.

Talos, in cooperation with CERT.NGO, investigated another compromise by the Turla threat actor, with a new backdoor quite similar to TinyTurla, that we are calling TinyTurla-NG (TTNG). Our findings indicate that Polish non-governmental organizations (NGOs) are actively being targeted, with at least one of them supporting Ukraine. While NGOs aren’t directly involved in conflicts they frequently participate in providing aid to entities suffering through the conflicts. Aggressor parties may deem it strategically beneficial to monitor such NGOs to keep track of ongoing and potentially new aid packages for their victims.

Turla has been widely known to target entities across the world using a huge set of offensive tools in geographies including the U.S., European Union, Ukraine and Asia. They’ve previously used malware families such as CAPIBAR and KAZUAR to target Ukrainian defense forces. After Crutch and TinyTurla, Turla has now expanded its arsenal to include the TinyTurla-NG and TurlaPower-NG malware families, while also widening its net of targets to NGOs. This activity signals the adversary’s intention to expand both their suite of malware as well as a set of targets to support Russia’s strategic and political goals.

Talos identified the existence of three different TinyTurla-NG samples, but only obtained access to two of them. This campaign’s earliest compromise date was Dec. 18, 2023, and was still active as recently as Jan. 27, 2024. However, we assess that the campaign may have started as early as November 2023 based on malware compilation dates. 

In this campaign, Turla uses compromised WordPress-based websites as command and control endpoints (C2) for the TTNG backdoor. The operators used different websites running vulnerable WordPress versions (versions including 4.4.20, 5.0.21, 5.1.18 and 5.7.2), which allowed the upload of PHP files containing the C2 code consisting of names such as: rss-old[.]php, rss[.]old[.]php or block[.]old[.]php

TinyTurla-NG uses PowerShell and a command line to run arbitrary commands

During the campaign’s three-month run, different C2 servers were also used to host PowerShell scripts and arbitrary commands that could then be executed on the victim machine.

Like TinyTurla, the malware is a service DLL, which is started via svchost.exe. The malware code itself is different and new. Different malware features are distributed via different threads. The malware is using Windows events for synchronization. In the DLL’s ServiceMain function, the first main malware thread is started.

The InitCfgSetupCreateEvent function initializes the config variables and the event which is used for synchronization later on. 

This thread then starts two more threads via the CheckOSVersion_StartWorkerThreads function.

After checking the PowerShell and Windows versions, the first thread starts to beacon to the C2 by sending a campaign identifier (“id”) and the message “Client Ready” to register the successful infection with the C2. This is done in the C2_client_ready function in the screenshot below.

If the registration is successful, the TTNG backdoor will ask the C2 for a task to execute (gettask_loop function). The second thread, which was started by the CheckOSVersion_Start_WorkerThreads function, is responsible for executing the task command sent from the C2. It waits until the TTNG backdoor has received the response from the C2. The synchronization between the two threads is performed via the Windows event mentioned earlier. The first thread triggers the event (in the thread1_function) once it has successfully received the task from the C2.

The tasks can be executed either using a PowerShell or command (cmd.exe) shell. The decision is made based on the PowerShell version running on the victim machine.

When executing commands via cmd.exe or PowerShell.exe, TinyTurla-NG will create pipes to input and read the output of the commands. While executing commands via cmd.exe, the backdoor first executes the command chcp 437 > NULexecute to set the active console page to 437, i.e., the U.S., and then execute the commands issued by the C2. 

However, while executing commands via PowerShell.exe, TinyTurla-NG will additionally execute the following PowerShell cmdlet to prevent the recording of command history:

Set-PSReadLineOption -HistorySaveStyle SaveNothing

In addition to executing the content of the task received from the C2 directly e.g., C:\windows\system32\malware.exe, the backdoor will accept the following command codes from the C2. These command codes can be meant for administering the implant or for file management:

• “timeout”: Change the number of minutes the backdoor sleeps between asking the C2 for new tasks. The new timeout is one minute multiplied by the timeout parameter sent by the C2. For example, if the C2 sends the task “timeout 10”, then the backdoor will now sleep for 10 minutes. If it is given a third parameter, the fail counter is changed, too.

• “changeshell”: This command will instruct the backdoor to switch the current shell being used to execute commands, i.e., from cmd.exe to PowerShell.exe, or vice versa.
• “changepoint”: This command code is used by the C2 to retrieve the result of command(s) executed on the infected endpoint. The endpoint will also return logging messages to the C2 server it has collected for administrative commands executed since "changepoint" was last issued such as:

[+] Short Timer changed. New Short Timeout is 1 minute

• “get”: Fetch a file specified by the C2 using an HTTP GET request and write it to the specified location on disk.
• “post”: Exfiltrate a file from the victim to the C2, e.g., post C:\some_file.bin.
• “killme”: Create a BAT file (see below) with a name based on the current tick count. Then, use the BAT file to delete a file from the disk of the victim machine, e.g., killme <filename>. The BAT file is executed via cmd.exe /c <BAT-file-name>.bat. 

The killme command generates a batch file with the content below. It is interesting to note that the backdoor DLL is essentially a service, however, the batch script deletes a registry key in HKCU\SW\classes\CLSID and restarts explorer[.]exe indicating an attempt to create persistence using COM hijacking, a tactic Turla has used in the past to establish persistence for their malware.

Registry key deleted:

HKEY_CURRENT_USER\Software\Classes\CLSID\{C2796011-81BA-4148-8FCA-C6643245113F}

The BAT file is created from the template where the first two “%s” are replaced with the DLL name and the last one with the name of the BAT file itself to delete both artifacts from the disk.

TurlaPower-NG and its exfiltration capabilities

Talos also discovered malicious PowerShell scripts we’re calling “TurlaPower-NG”, written to infected endpoints via the TTNG backdoor. The scripts consist of the C2 URL and target file paths. For each file path specified, the script will recursively enumerate files and add them to an archive on disk. TurlaPower-NG takes specific care to exclude files with the “.mp4” extension from being added to the archive. The attackers had a specific interest in key material used to secure the password databases and popular password management software, adding related files to the archive:

The archive is a “.zip” extension whose name is generated on the fly by generating a new GUID which is used as the archive name. The archive file is then exfiltrated to the C2 using HTTP/S POST requests along with a log of the activity performed being sent to the C2 as well. The log consists of:

• Name of the archive file (or part) POSTed to the C2.
• Number of files in the archive along with the archive size.

C2 setup and operations

All of the C2 servers discovered so far consist of legitimate, vulnerable WordPress-based websites compromised by Turla to set up their C2 servers. Once compromised the operators set up scripts, logging and data directories to operate their C2 servers.

Directory and file structure

The C2’s directories and files setup consists of three key components:

• C2 scripts: Turla set up PHP scripts ending with extensions — “.old.php” — in certain directories of the compromised websites. The URLs for these PHP-based C2s were then coded into the TTNG backdoors consisting of two C2 URLs per sample.
• Logging: In addition to the C2 PHP scripts, the adversary also set up the logging of infections to keep track of infected systems and commands being issued to them. The logging mechanism of the C2 generates three log files on the C2 server:
  • _log[.]txt: A log of all infected endpoints beaconing into the C2.
  • result[.]txt: A log of all messages received from the TTNG backdoor.
  • tasks[.]txt: A log of all commands issued to the infected hosts.
• Data directories: TTNG and TurlaPower-NG both support the exfiltration of files to the C2 server. The C2 server stores stolen data in directories separate from the logging directories.

C2 communication process

The TinyTurla-NG backdoor uses a specific Identifier, “id” value in its HTTP form data whenever it communicates with the C2 server. This ID value is an eight-character phrase hardcoded into the backdoor. 

This same identifier value is then used to create directories for log files on the C2 server indicating that the C2 server maintains different log files for different identifiers.

After registering the victim on the C2 server, the backdoor sends out a gettask request, similar to the one below. The C2 can answer this with special commands or just the file that is supposed to be executed on the infected machine. 

Depending on the PowerShell version running on the victim machine, the C2 task commands are piped into a PowerShell or cmd[.]exe shell. 

Coverage

Ways our customers can detect and block this threat are listed below.

Cisco Secure Endpoint (formerly AMP for Endpoints) is ideally suited to prevent the execution of the malware detailed in this post. Try Secure Endpoint for free here.

Cisco Secure Web Appliance web scanning prevents access to malicious websites and detects malware used in these attacks.

Cisco Secure Email (formerly Cisco Email Security) can block malicious emails sent by threat actors as part of their campaign. You can try Secure Email for free here.

Cisco Secure Firewall (formerly Next-Generation Firewall and Firepower NGFW) appliances such as Threat Defense Virtual, Adaptive Security Appliance and Meraki MX can detect malicious activity associated with this threat.

Cisco Secure Malware Analytics (Threat Grid) identifies malicious binaries and builds protection into all Cisco Secure products.

Umbrella, Cisco's secure internet gateway (SIG), blocks users from connecting to malicious domains, IPs and URLs, whether users are on or off the corporate network. Sign up for a free trial of Umbrella here.

Cisco Secure Web Appliance (formerly Web Security Appliance) automatically blocks potentially dangerous sites and tests suspicious sites before users access them.

Additional protections with context to your specific environment and threat data are available from the Firewall Management Center.

Cisco Duo provides multi-factor authentication for users to ensure only those authorized are accessing your network.

Open-source Snort Subscriber Rule Set customers can stay up to date by downloading the latest rule pack available for purchase on Snort.org.

IOCs

IOCs for this research can also be found at our GitHub repository here.

Hashes

267071df79927abd1e57f57106924dd8a68e1c4ed74e7b69403cdcdf6e6a453b
d6ac21a409f35a80ba9ccfe58ae1ae32883e44ecc724e4ae8289e7465ab2cf40

Domains

hanagram[.]jp
thefinetreats[.]com
caduff-sa[.]ch
jeepcarlease[.]com
buy-new-car[.]com
carleasingguru[.]com