Sophos

W32/Bobax-D

Category
Type
What to do
Prevalence low high

Summary

 
Affected operating systems Windows
Characteristics
  • Installs itself in the registry
Included in our products from February 2005 (3.90)
Protection available since 12 January 2005 08:47:37 (GMT)
Detected by All Sophos products

Action

More Information

W32/Bobax-D is a Sasser-like worm that uses the MS04-011 (LSASS.exe) vulnerability to propagate.

When run, W32/Bobax-D creates a helper dll in the temp folder with a random name. When the dll is loaded the executable component copies itself to the Windows system folder under a random name.

This dll is injected into Explorer as a separate thread, so is not visible as a separate process.

The worm listens on a randomly chosen tcp port which the worm then includes in outbound traffic so infected systems can connect back.

W32/Bobax-D also carries an email relay module, allowing infected computers to be used for transmission of unsolicited emails.

W32/Bobax-D will also attempt to disable the Microsoft Windows firewall. W32/Bobax-D is a Sasser-like worm that uses the MS04-011 (LSASS.exe) vulnerability to propagate.

When run, W32/Bobax-D creates a helper dll in the temp folder with a random name. When the dll is loaded the executable component copies itself to the Windows system folder under a random name.

W32/Bobax-D sets the following registry entries in order to auto-start on user logon:

HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/RunServices/
<random name> = <path to worm>

HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/Run/
<random name> = <path to worm>

This dll is injected into Explorer as a separate thread, so is not visible as a separate process.

The worm listens on a randomly chosen tcp port which the worm then includes in outbound traffic so infected systems can connect back.

W32/Bobax-D also carries an email relay module, allowing infected computers to be used for transmission of unsolicited emails.

W32/Bobax-D attempts to modify the HOSTS file located at %SYSTEM \Drivers\etc\HOSTS, mapping selected anti-virus websites to the address 255.255.255.255 in an attempt to prevent access to these sites.

W32/Bobax-D will also attempt to disable the Microsoft Windows firewall.

W32/Bobax-D will also set the following registry entry:

HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess
Start
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