Trojan-Downloader:W32/Agent.FCG

Classification

Malware

Trojan-Downloader

W32

Trojan-Downloader:W32/Agent.FCG

Summary

This trojan arrives on the system as a downloaded file of another malware installation package. The first reported instance of the malware was during the recent (October 2007) PDF exploit attack that is detected as Exploit:W32/AdobeReader.L. Upon execution, this trojan downloads and executes another trojan file in the compromised system, currently detected as Trojan-Dropper:W32/Agent.CMW.

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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User Guide

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Submit a sample

Submit a file or URL for further analysis.

Technical Details

Being a means to an end, this trojan's role is primarily to download another trojan and execute it on the user's system.Utilizing Windows' own Background Intelligent Transfer Service (BITS), which Windows also uses for Downloading Updates to a user's system, the malware will attempt to download the target payload file from the following URL:

  • http://kerk20wjpz8.info/[REMOVED]/[random].gif

This method proves to be effective in bypassing firewall applications.For the purpose of bypassing antivirus scanners, this trojan's downloaded payload file is encrypted. Once downloaded, it will then decrypt and execute the file in memory, thus avoiding antivirus scanners that work mostly if a physical file is present.In case the file download via BITS has not been successful, it will attempt to download the same payload file again, this time using a direct download via Windows API functions.The payload file downloaded is currently detected as Trojan-Dropper:W32/Agent.CMW.When this file has been successfully executed, the malware will then perform a cleanup by deleting itself from the system.