This page shows details and results of our analysis on the malware W32/

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Threat Detail

  • Malware Type: Virus
  • Malware Sub-type: Parasitic
  • Protection Added: 2007-02-12

W32/ is a file infecting virus. It searches for executable files on the infected machine to prepend its viral code. It is also responsible for dropping a .DLL file, which downloads a password stealing trojan from a website.


Minimum Engine


File Length

61,169 bytes

Description Added


Description Modified


Malware Proliferation

Upon execution, this variant copies itself into %WinDir%\Uninstall folder as rundl132.exe (note the L1, not LL of .DLL) and adds a registry entry to activate itself on reboot. It also creates the following registry entries:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DownloadManager
  • HKEY_LOCAL_MACHINE\SOFTWARE\Soft\DownloadWWW\auto: "1"

It drops a .DLL file named RichDll.dll (detected as W32/HLLP.Philis.dll since the 4896 DATs) in %WinDir%. It then injects this dll into processes Explorer.exe and IExplore.exe. This thread attempts to download other objects from the following locations:


At the time of writing this web address was unavailable. It is believed (based on historical Philis variants) that these files are password-stealing trojans, typically from the PWS-Lineage family.

W32/ searches for executable files and prepends its viral code to target files.

The virus creates files with the name "_desktop.ini" in every folder that it visits while looking for executable files to infect. This is created as a hidden system file and contains the date on which virus was executed to visit the folder in which the file resides. The date is shown in yyyy/mm/dd format.

The virus tries to spread via existing network shares. It searches for all active machines within the subnet. When it finds an active machine it sends an ICMP ping request and waits for a response. 
After getting the ping response it tries to access the ADMIN$, IPC$ and any other shares that might exist on the machine.

If the virus is able to access a shared resource, it first copies "_desktop.ini" to the root of the share to mark the share as visited and then infects executables present in the share.

While infecting executables via a network share the virus does not limit itself to infecting specific file names as mentioned above. In the case of a shared printer, the viruses' infection routine effectively creates printer job to print the date as contained in "_desktop.ini" file that the virus tries to copy.

  • Presence of %WinDir%\RichDll.dll
  • Presence of registry entries as described
  • Presence of files named _desktop.ini in many folders.
    • These files have the system (S) and hidden (H) attributes set
    • These files are detected as W32/HLLP.Philis.ini
  • Increase in size of EXE files
  • Increase in disk activity (read and write)
  • HTTP network traffic to the aforementioned web address
  • W32/ is a file infecting virus. Infection starts with manual execution of the binary. For spreading, the virus also relies on improperly configured/protected (open) shared drives.

    Detection is included in our BETA DAT files and will also be included in the next scheduled DAT release. In addition to the DAT version requirements for detection, the specified engine version (or greater) must also be used.

    Additional Windows ME/XP removal considerations