Licat.C arrives on the system as a downloaded file via a link that is spammed through MSN Messenger. Below is a sample message:
It searches for the location of MSN Messenger installed on the system through the following registry key:
- [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\MSNMSGR.EXE\Path]
When found, it attempts to rename the original MSN Messenger application client to msgs.exe. It then copies itself to the folder using the filename msnmsgr.exe so that it will start each time that MSN Messenger is started by the user. The copy then launches the renamed Messenger file.
Licat.C's backdoor component (some instances are detected as Backdoor.Win32.MSNMaker.v) connects to the following website:
This websites contains links to the following malicious IP address:
It uses a vulnerability in the meta tag, which has a malicious IP address on its content. Vulnerable web browsers will automatically execute the file when this site is accessed.
When this IP address is accessed, it will again download from the following websites and execute other malware on the system using the following filenames:
- https://www.uglyphotos.net/[REMOVED] - alfa.exe
- https://www.uglyphotos.net/[REMOVED] - sprT.exe
- https://www.uglyphotos.net/[REMOVED] - Xinstall.exe
The downloaded file, sprT.exe, is the one responsible for the pop-up messages spammed through MSN Messenger. This is also detected as IM-Worm.Win32.Licat.c. Below is the pop-up message used:
- lol check:P http://peopleonline.pe.funpic.de/[removed].PIF
When this URL link is clicked, a copy of Licat.C will be downloaded on the system.
The two other downloaded files are a trojan dropper (Xinstall.exe) and an adware application (alfa.exe) respectively. They are now detected asTrojan-Dropper.Win32.PurityScan.ag and not-a-virus:AdWare.Win32.Softomate.q.