Threat Description



Aliases: Agent.AUM, Threat Name, Acanze
Category: Malware
Type: Worm
Platform: W32


Agent.AUM is a trojan that drops and executes several other malware files onto the computer system.

In general, trojan droppers are usually standalone programs that drop different types of standalone malware (trojans, worms, backdoors) to a system. A typical trojan dropper is a file that contains a few other files compressed inside its body. When a trojan dropper is run, it extracts all files it contains to a folder (usually temporary folder) and runs all of them simultaneously.

Aside from being a dropper, this trojan also has the ability to steal usernames, passwords, and other system information from the victim's computer.


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.


Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Technical Details

Agent.AUM is a Themida packed trojan that arrives on the system with the filename of Windows Genuine Advantage Patch.exe.

Upon execution, it drops the following files in the Windows System directory:

  • ldapi32.exe (17 KB) - Detected as Backdoor.Win32.Cakl.a
  • ntcvx32.dll (22 KB) - Detected as Trojan-Spy.Win32.Delf.qb
  • ntswrl32.dll (9 KB) - Detected as Backdoor.Win32.Cakl.a
  • vssms32.exe (1,696 KB) - A copy of itself

It checks the existence of the following mutex to ensure that there's only one instance of itself running in memory:

  • TURKO3

In creates the following autostart registry entry:

  • [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]vssms32 = "{systemdir}\vssms32.exe"

It also creates the following registry entry to allow itself to bypass the Windows Firewall:

  • [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List] {systemdir}\vssms32.exe = "{systemdir}\vssms32.exe:*:Enabled:Dnode"

It modifies the following registry keys:

  • [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal]
  • [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Network]

- and changes them it to:

  • [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\]
  • [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\]

This is done in order to prevent the user from successfully booting into Safe Mode.

This trojan tries to steal user account names and passwords of the following known applications:

  • Firefox
  • ICQ
  • Internet Explorer
  • MSN Messenger
  • Outlook
  • RAS

It also tries to get system information such as:

  • CapsLock State
  • Computer Name
  • CPU Name
  • CPU Speed
  • Free Disk Space
  • Local Host Name
  • NumLock State
  • Operating System
  • Resolution
  • Screen Captures of the System
  • ScrollLock State
  • Temporary and System Folders Location
  • User Name
  • Windows Language

Agent.AUM also attempts to log keystroke events and saves them to the following file located at the Windows folder:

  • HKR32.ASM

Below is an example of the HKR32.ASM file. It shows the user's logged keystrokes:


F-Secure Anti-Virus detects this malware with the following updates:

Detection Type: PC
Database: 2006-08-15_07


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