MuddyWater is an APT group who's targets have mainly been in the Middle East, such as the Kingdom of Saudi Arabia, the United Arab Emirates, Jordan, Iraq ... with a focus on oil, military, telco and government entities.
The group is using Spear Phishing attacks as an initial vector. The email contains an attached word document which tries to trick the user into enabling macros. The attachment's filename and its content are usually tailored towards the target, such as the language used.
In the below example, we will look at the behavior of the following malware sample:
Filetype: MS Word Document
This specific malware sample is for an Arabic speaking victim targeted at Jordan, where the filename "معلومات هامة.doc" can translate into "important information.doc". Other variants contain content in Turkish, Pakistani ...
The file shows blurry text in Arabic, with a message telling the target to enable content (and therefore macros) to unlock the content of the document.
Once the user clicks on "Enable Content", we're able to see the following behaviors on RSA NetWitness Endpoint.
1- The user opens the file. In this case, the file was opened from the Desktop folder, but if it was from his email, it would have shown from "outlook.exe" instead of "explorer.exe"
2- The malware uses "rundll32.exe" to execute the dropped file (C:\ProgranData\EventManager.log), allowing to evade detection
3- Powershell is then used to decode the payload of another dropped file ("C:\ProgramData\WindowsDefenderService.ini") and executes it. Having the full arguments of the Powershell command, it would be possible for the analyst to use it to decode the content of the "WindowsDefenderService.ini" file for further analysis
4- Powershell modifies the "Run" Registry key to run the payload at startup
5- Scheduled tasks are also created
After this, the malware will continue execution after a restart (this might be as a layer of protection against sandboxes).
6- The infected machine is restarted
7- an additional powershell script "a.ps1" is dropped
8- Some of the Windows security settings are disabled (such as Windows Firewall, Antivirus, ...)
By looking at the network activity on the endpoint, we can see that powershell has generated a number of connections to multiple domains and IPs (possible C2 domains).
To look into the network part in more details, we can leverage the captured network traffic on RSA NetWitness Network.
We can see, on RSA NetWitness Network, the communication from the infected machine (192.168.1.128) to multiple domains and IP addresses over HTTP that match what has been originating from powershell on RSA NetWitness Endpoint.
We can also see that most of the traffic is targeting "db-config-ini.php". From this, it seems that the attacker has compromised different legitimate websites, and the "db-config-ini.php" file is owned by the attacker.
Having the full payload of the session on RSA NetWitness network, we can reconstruct the session to confirm that it does in fact look like beaconing activity to a C2 server.
Even though the websites used might be legitimate (but compromised), we can still see suspicious indicators, such as:
- POST request without a GET
- Missing Headers
- Suspicious / No User-Agent
- High number of 404 Errors
We can see how the attacker is using legitimate, trusted, and possibly white-listed modules, such as powershell and rundll32, to evade detection. The attacker is also using common file names for the dropped files and scripts, such as "EventManager" and "WindowsDefenderService" to avoid suspicion from analysts.
As shown in the below screenshot, even though "WmiPrvSE.exe" is a legitimate Microsoft files (it has a valid Microsot signature, as well as a known trusted hash value), but due to its behavioral activity (as shown in the Instant IOC section), we're able to assign a high behavioral score of 386. It should also be noted that any of the suspicious IIOCs that have been detected could trigger a real time alert over Syslog or E-Mail for early detection, even though the attacker is using advanced techniques to avoid detection.
Similarly, on the network, even though the attacker is leveraging (compromised) legitimate sites, and using standard known protocols (HTTP) and encrypted payloads, to avoid detection and suspicion, it is still possible to detect those suspicious behaviors using RSA NetWitness Network, and look for indicators such as Post no Get, suspicious user agents, missing headers, or other anomalies.
The following are IOCs that can be used to look if activity from this APT currently exists in your environment.
This list is not exhaustive and is only based on what has been seen during this test.
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