FireEye have recently detected a cerber ransomware campaign with Exploit Guard, a new feature of FireEye Endpoint Security (HX).
According to the security company, the ransomware came in the guise of a Microsoft Word document attached to emails. FireEye say the document contains a malicious macro that contacts an attacker-controlled website to download and install the cerber ransomware.
Ransomware is a common method of cyber extortion for financial gain, it typically involves users being unable to interact with their files, applications or systems until a random is paid.
Upon identifying the cerber ransomware, a FireEye research team were able to shut it down within hours of detecting the activity.
“FireEye hasn’t seen any additional infections from this attacker since shutting down the C2 server, although the attacker could configure one or more additional C2 servers and resume the campaign at any time,” a company statement read.
Here is the cerber ransomware attack cycle that FireEye observed in eight steps:
- Target receives and opens a Word document.
- Macro in document is invoked to run PowerShell in hidden mode.
- Control is passed to PowerShell, which connects to a malicious site to download the ransomware.
- On successful connection, the ransomware is written to the disk of the victim.
- PowerShell executes the ransomware.
- The malware configures multiple concurrent persistence mechanisms by creating command processor, screensaver, startup.run and run once registry entries.
- The executable uses native Windows utilities such as WMIC and/or VSSAdmin to delete backups and shadow copies.
- Files are encrypted and messages are presented to the user requesting payment.
The most common way to deliver ransomware is via Word documents with embedded macros or a Microsoft Office exploit.
FireEye claim its Exploit Guard detects both of these attacks at the initial stage of the attack cycle.