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Trojan-Downloader:W32/Mebroot.gen!B

Classification

Category: Malware

Type: Trojan-Downloader

Aliases: Trojan-Downloader:W32/Mebroot.gen!B

Summary


Trojan-Downloader:W32/Mebroot.gen!B is a generic detection that identifies the downloader program responsible for fetching the installer for the Mebroot rootkit.

Generic detections are broad patterns of code or behavior that are used by security software to identify programs or files. If you suspect the detected file was incorrectly identified, go to: Removal: Resolve a False Positive.

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.

Resolve a False Positive

Security programs will sometimes unintentionally identify a clean program or file as malicious if its code or behavior is similar to a known harmful program or file. This is known as a False Positive. In most cases, a False Positive is fixed in a subsequent database release. If you suspect the detected file is a False Positive, you can:

Knowledge Base

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About the product

See the manual for your F-Secure product on the Help Center.

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Submit a sample

Submit a file or URL for further analysis.

Technical Details


This malware is discussed in further detail in the following Labs Weblog posts:

The downloader is known to be distributed to users via a malicious website (driveby download) or via an exploit.

Activity

When active, the downloader downloads an encrypted file on port 443 or 80 from:

  • http://bcoxgcgxes.com (encrypted file)

where (encrypted file) is a defined string. This string is unique in every sample.

Once downloaded, the encrypted file is first saved in an allocated memory where it will be decrypted, then saved to a file in a temporary folder. The file will then be executed.

The encrypted file is encrypted with an RC2 encryption algorithm. The Cipher Hash that is used in the decryption is based on a defined string that is also unique in every sample.