This trojan attempts to download a file (presumably malicious) from a randomly generated domain.
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.
On first running, Trojan:W32/Murofet.A checks if the system already has a specific key value set:
This key value acts as an infection marker and is set by another program (presumably an accomplice to this malware). If this infection marker is found, Murofet.A will not proceed any further.
If the infection market is not present, this malware will spawn a thread that downloads an arbitrary file from the Internet.
To download the file, the malware connects to a domain whose URL is randomly generated based on the current system date and time. The pattern of the generated URL is:
where the [generated_domain] is a series of lowercase ascii characters from a to z and [generated_tld] will be one of the following: "biz", "info", "org", "net", or "com".
Examples:
If there is at least one successful download, the malware will save the downloaded file to the %TEMP% directory, then verify the file's integrity against an embedded public key that is generated by the author using the SHA hashing algorithm. If verification is successful, the downloaded file is executed.
If the download or verification is not successful, the malware will move on to generate another download URL; it attempts to repeat the process up to a maximum of 800 times or until it is successful.
At the time of testing, there were no successful file downloads.