Mitglieder.H

Classification

Malware

Trojan

W32

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.

Automatic action

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.

Suspect a file is incorrectly detected (a False Positive)?

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 detection database 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.

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Submit a sample

Submit a file or URL for further analysis.

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.