A type of worm that replicates by sending complete, independent copies of itself over a network.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
For general instructions on disinfecting a local network infection, please see Eliminating A Local Network Outbreak.
Worm:W32/Agent.T drops several copies of itself onto the system and downloads other additional malware from the Internet.
Upon execution, Agent.T drops the following files:
- %windir%\yqqty.exe - A copy of itself.
It modifies the following autostart registry entry to enable its automatic execution every system boot-up:
- [HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon] Userinit=%windir%\system32\userinit.exe,%windir%\yqqty.exe
Note: The default value is Userinit=%windir%\system32\userinit.exe
It may drop a copy of itself to several drives. The Autorun.inf file, which is a configuration file used to automatically execute the malware when a directory or drive is being opened, is also dropped together with the main executable file.
Agent.T downloads the following files from the Internet:
It then saves the files to the Windows directory using the following filenames:
One of the text files contains the following download sites:
The downloaded files are also trojan-downloaders that are now detected as Trojan-Downloader:W32/Small.EJW and Trojan-Downloader:W32/Small.ELM.