CetaRAT was seen for the first time in the Operation SideCopy APT. Now it is continuously expanding its activity since then. We have been tracking this RAT for a long time and observed an increase in targeting the Indian government agencies.
The CetaRAT infection chain starts with a Spear phishing mail with a malicious mail attachment. The attachment can be a zip file that downloads an HTA file from a remote, compromised URL. Once this HTA file is executed using mshta.exe, it drops and executes the CetaRAT payload that starts the CnC activity.
After HTA file execution, we observed two different behaviours:
The second method observed, creating and running batch files at random name folder on C drive on the victim’s machine, which contains the instructions to add registry entry at “HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run” with the path of CetaRAT executable payload. In this variant, the executable is dropped at %AppData/Roaming% location.
The CetaRAT is C#-based RAT family which exfiltrates the data from the user and sends it to the CnC server. Once it is executed, first, it will check the running AV product details from the machine with function Getans() and send details to the CnC server.
Function Start() uses the get details from machines like computer name, OS details, IP address, memory details, running processor, etc., and uploads it to CnC Server. This data is encrypted before uploading it to CnC.
The GetIP() function is used in this RAT activity to get the running machine’s IP information. Here domain “checkip.dydnd.org” is used for this purpose. This function returns the machine’s IP address.
In the next activity, the RAT uses commands to exfiltrate the data and for file operations, below are commands details-
After gathering information from the user’s machine, CetaRAT uses the RC4 algorithm to encrypt data before uploading it to the CnC server.
Once the data is encrypted, it will exfiltrate to the CnC server using the POST HTTP method. We can see three CnC server IPs mentioned in the code below, with the keyword “ceta”.
CetaRAT is Exfiltrating data that simply deliver mechanisms and aggressively infect the victim. It might leak sensitive data from a government organization, which impacts harmful activities in the countries. We recommend our customers not to access suspicious emails/attachments and keep their AV software up-to-date to protect their systems from such complex malware.