Mitglieder.H

Classification

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

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

Check for the latest database updates
First check if your F-Secure security program is using the latest updates, then try scanning the file again.
Submit a sample
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.
Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
Exclude a file from further scanning
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note: You need administrative rights to change the settings.

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.