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Mitglieder.H

Classification

Category: Malware

Type: Trojan

Aliases: Mitglieder.H

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

Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.

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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.