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Panda Protection

Virus Encyclopedia

Welcome to the Virus Encyclopedia of Panda Security.

Mytob.NH

Threat LevelHigh threatDamageSevereDistributionNot widespread
Common name:Mytob.NH
Technical name:W32/Mytob.NH.worm
Threat level:Medium
Type:Worm
Effects:   It spreads and affects other computers. 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 uses anti-monitoring techniques in order to prevent it being detected by antivirus companies. It spreads , via email.
Affected platforms:

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

First detected on:March 5, 2006
Detection updated on:March 5, 2006
StatisticsNo

Brief Description 

    

Mytob.NH is a worm that spreads by copying itself, without infecting other files.

 

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 terminates processes belonging to security tools, such as antivirus programs and firewalls, leaving the computer defenseless against attacks from other malware; it changes the security settings of Internet Explorer, decreasing its security level; it opens one or more ports to allow remote access to the computer and takes action that compromises user confidentiality; it awaits remote-control orders received through IRC.

 

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

 

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

  • It prevents scanning tools from running, such as Windows Registry Editor, FileMonitor, etc.
  • It terminates its own execution if it detects that a memory dump program is running, such as Procdump.
  • Its code is encrypted and it is only decrypted when it is going to run. Because of this, its code is not legible through a memory dump.
  • It terminates its own execution if it detects that a debugging program is active.

 

Mytob.NH 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.
  • Email: sending emails that include a copy of itself as an attachment. The computer is infected when the attachment is run.