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IM-Worm:W32/Pykse.A
Summary
A type of worm that spreads on vulnerable Instant Messaging (IM) networks.
Disinfection
Allow F-Secure Anti-Virus to disinfect the relevant files.
For more general information on disinfection, please see Removal Instructions.
Additional Details
IM-Worm:W32/Pykse.A is an instant messaging worm that uses the APIR for the Instant Messaging application Skype to send messages with malicious URL links.
When IM-Worm:W32/Pykse.A is executed, it will show a picture of a lightly dressed woman as below:
Note: the image has been blurred.
For related details, the F-Secure Weblog has a post on the matter.
Installation
When executed, the worm drops the following files:
It adds the following auto start registry entry to enable its automatic execution upon boot up:
It also adds the .DLL component as a BHO (Browser Helper Object) so that once the Internet browser is loaded, the malware is also loaded simultaneously.
IM-Worm:W32/Pykse.A creates the following key, to save some of its installation details:
It creates the following mutexes to signify each malicious routine. No duplicate mutex could be created to ensure that only these three mutexes are present in the memory at one particular time:
Propagation
IM-Worm:W32/Pykse.A spreads via Skype by sending a message with a malware link to all online friends in Skype' contact list using Skype API.
The message is randomly chosen from the following list:
It sets the Skype user's status to DND (Do not Disturb) so that the user cannot be actively notified of incoming calls or messages.
It visits the following non-malicious links:
Moreover the following site is also visited, which probably acts as a counter for the number of infected machines:
Detection
F-Secure Anti-Virus detects this malware with the following updates:
[FSAV_Database_Version]
Version = 2007-04-16_01
When IM-Worm:W32/Pykse.A is executed, it will show a picture of a lightly dressed woman as below:
Note: the image has been blurred.
For related details, the F-Secure Weblog has a post on the matter.
Installation
When executed, the worm drops the following files:
- %sysdir%\Invisible002.dll - contains most of malicious code
- %sysdir%\system32\Skype.exe
It adds the following auto start registry entry to enable its automatic execution upon boot up:
- HKCU\Software\Microsoft\Windows\CurrentVersion\Run
SkypeStartup = "%sysdir%\Skype.exe"
- HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
SkypeStartup = "%sysdir%\Skype.exe"
It also adds the .DLL component as a BHO (Browser Helper Object) so that once the Internet browser is loaded, the malware is also loaded simultaneously.
IM-Worm:W32/Pykse.A creates the following key, to save some of its installation details:
- HKCU\Software\SkypeWorm\cfg
It creates the following mutexes to signify each malicious routine. No duplicate mutex could be created to ensure that only these three mutexes are present in the memory at one particular time:
- Skype Worm spreader mutex - Spreading routine
- Skype Worm server mutex1 - Other routines
- aaa111226 - Iexplore.exe injection
Propagation
IM-Worm:W32/Pykse.A spreads via Skype by sending a message with a malware link to all online friends in Skype' contact list using Skype API.
The message is randomly chosen from the following list:
It sets the Skype user's status to DND (Do not Disturb) so that the user cannot be actively notified of incoming calls or messages.
It visits the following non-malicious links:
- http://aras.lookingat.us/index.htm
- http://asilas.my-php.net/index.html
- http://bobodada.3-hosting.net/index.html
- http://bobos45.bebto.com/index.html
- http://gogo442.hatesit.com/index.html
- http://jackdaniels.110mb.com/index.html
- http://timboss.1majorhost.com/index.html
- http://zozole.php0h.com/index.html
Moreover the following site is also visited, which probably acts as a counter for the number of infected machines:
- http://aras.allfreehost.net/c[REMOVED]nt.php
Detection
F-Secure Anti-Virus detects this malware with the following updates:
[FSAV_Database_Version]
Version = 2007-04-16_01