Threat Descriptons



Category :


Type :


Aliases :

Backdoor.Kelihos.[variant], Kelihos.[variant]


The Kelihos backdoor is able to rope the affected system into the Kelihos botnet , which is typically used to send out spam email messages.


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

Kelihos malware is often dropped and installed as the payload of other malware, such as trojan-downloaders. Some variants are also distributed via links to malicious websites that are circulated through the Facebook social network.

Once the malware has been installed on a system, it typically tries to contact a remote server and download its other components, including a backdoor that gives remote attackers further control over the affected system.

The backdoor also connects the system to a botnet under the attacker's control. The botnet (referred to as the Kelihos or Hlux botnet) is built on a peer-to-peer or P2P infrastructure, so commands are relayed through other similarly infected machines from the attacker's command and control server (a structure that makes this kind of botnet much harder to detect and shut down). Once included in the botnet, the affected system may be instructed to download other malware, or be used to send spam email messages to other victims. It may also be directed to perform other malicious actions, such as stealing Bitcoins.

When present on the system, the Kelihos malware is able to function as an information stealer. The malware looks for and steals login credentials from certain installed programs, such as FTP and mail clients and web browsers. It also harvests email addresses stored on the affected system.

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