Threat Description

Mitglieder.H

Details

Aliases: Mitglieder.H
Category: Malware
Type: Trojan
Platform: W32

Summary


Mitglieder.H is a descendant of the Mitglieder trojan family with the ability to spread to computers infected with the Mydoom.A worm.

The main payload of the worm is a backdoor / SMTP proxy that listens on TCP port 35555. The payload includes other parts like disabling antivirus software and reporting of infected computers.



Removal


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.



Technical Details


System Infection

When run, the worm copies itself as SYSTEM.EXE to the Windows System directory and creates the following entry in the System Registry:

[HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run]  "ssgrate.exe" = "%winsysdir%\system.exe"   

where %winsysdir% is the name of Windows System directory.

It also creates another key in the Registry where it stores its internal variables:

[HKCU\SOFTWARE\DateTime] 			  
Network Propagation

To spread Mitglieder.H scans random IP addresses for open TCP port 3127. Exploiting the backdoor installed by Mydoom.A it copies itself to those hosts.

Backdoor and SMTP proxy

The main component of the payload is a TCP backdoor / SMTP proxy that listens on port 35555. Through the backdoor a remote attacker can instruct the infected computer to build up a TCP connection and relay the traffic.

The backdoor component uses a list of URLs to PHP files where it reports the address of the infected computer along with the port number where the backdoor is sitting.

Disabling Security Software

The payload of Mitglieder.H contains a thread that terminates processes with the following names:

ATUPDATER.EXE  AVWUPD32.EXE  AVPUPD.EXE  LUALL.EXE  DRWEBUPW.EXE  ICSSUPPNT.EXE  ICSUPP95.EXE  UPDATE.EXE  NUPGRADE.EXE  ATUPDATER.EXE  AUPDATE.EXE  AUTODOWN.EXE  AUTOTRACE.EXE  AUTOUPDATE.EXE  AVXQUAR.EXE  CFIAUDIT.EXE  MCUPDATE.EXE  NUPGRADE.EXE  SMS.EXE  OUTPOST.EXE  
Remote Update

The worm contains several HTTP links that is uses to download and execute programs. At this moment the links are inaccessible so the worm will not download anything.



Detection


Detection in F-Secure Anti-Virus was published on February 12th, 2004 in update:

Detection Type: PC
Database: 2004-02-12_02



Technical Details:Gergely Erdelyi and Alexey Podrezov; February 12th, 2004


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