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Threat LevelHigh threatDamageSevereDistributionNot widespread
Common name:OscarBot.XW
Technical name:W32/OscarBot.XW
Threat level:Medium
Effects:   It carries out damaging actions on the affected computer. It affects the productivity of the computer, the network to which it’s connected or other remote sites. It carries out actions that decrease the security level of the computer. It downloads files from several websites. It uses stealth techniques to avoid being detected by the user. It uses anti-monitoring techniques in order to prevent it being detected by antivirus companies. It spreads , across the Internet, via mapped drives, through shared network resources, through instant messaging, by infecting files that are then distributed.
Affected platforms:

Windows 2003/XP/2000/NT/ME/98/95

First detected on:Jan. 4, 2010
Detection updated on:May 21, 2010
Proactive protection:
Yes, using TruPrevent Technologies

Brief Description 


OscarBot.XW is a virus that spreads to other computers by copying its code to other files or programs.


It affects productivity, preventing tasks from being carried out:

  • In the affected computer: it converts the computer into a platform for taking malicious action surreptitiously: spam sending, launch of Denial of Service attacks, malware distribution, etc.
  • In the local network: it generates a large amount of network activity and consumes bandwidth.


It reduces the security level of the computer: it awaits remote-control orders received through IRC; it changes system permissions, decreasing the security level.


OscarBot.XW prevents access from programs to websites of several companies related with security tools (antivirus programs, firewalls, etc.).


OscarBot.XW accesses several websites to download files, which it then runs. These can be any type of file, although they are normally malware.


It uses stealth techniques to avoid being detected by the user:

  • It uses techniques included in its code to hide itself while it is active.
  • It terminates processes corresponding to several security tools, such as antivirus programs and firewalls, to prevent detection.


It uses several methods in order to avoid detection by antivirus companies:

  • It terminates its own execution if it detects that it is being executed in a virtual machine environment, such as VMWare or VirtualPC.


OscarBot.XW uses the following propagation or distribution methods:

  • Exploiting vulnerabilities with the intervention of the user: exploiting vulnerabilities in file formats or applications. To exploit them successfully it needs the intervention of the user: opening files, viewing malicious web pages, reading emails, etc.
  • Via Internet, exploiting remote vulnerabilities: attacking random IP addresses, in which it tries to insert a copy of itself by exploiting one or more vulnerabilities.
  • Instant messaging: it sends links pointing to a copy of itself to all users included in the infected user's contacts list.
  • Computer networks (mapped drives): it creates copies of itself in mapped drives.
  • Computer networks (shared resources): it creates copies of itself in shared network resources to which it has access.
  • File infection: it infects different types of files, which are then distributed through any of the usual means: floppy disks, email messages with attachments, Internet download, files transferred via FTP, IRC channels, P2P file sharing networks, etc.


OscarBot.XW uses the following infection strategies:

  • Resident: once it has been run, the virus goes memory resident and stops functions belonging to the operating system. Therefore, every time the operating system or an application tries to access any of these functions, the virus will activate and infect new files.