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Net-Worm:W32/Koobface.BM

First posted on 17 October 2008.
Source: SecurityHome

Aliases :

There are no other names known for Net-Worm:W32/Koobface.BM.

Explanation :

A type of worm that replicates by sending complete, independent copies of itself over a network.

right]This worm attempts to spread via the Facebook social interaction website.

Execution
Upon execution, the malware will check itself to determine if it is running as "c:windowsolivari19.exe". If it is not, it will drop a copy of itself named as bolivari19.exe and will execute the file.

Once executed, the malware checks its marker c:windowsfmark2.dat to verify if has already been installed. If the file does not exist, the malware will display the following message:

• Title: Error
  Message: Error Installing Codec. Please contact support.

It will then create the file.

Next, the malware checks for existing Facebook cookies, in preparation for its installation and propagation routine. If no cookie is found, the malware just terminates and deletes itself.

The worm will then perform a post request (POST /fb/first.php?[...]=0&v=20&c=1&s=fb&l=en&ck=1&c_fb=1&c_ms=0&c_hi=0post) to a220[...].com, to receive the necessary data, such as the URL link of the malware executable file.

Registry Changes
On installation, the malware creates a registry key that allows the malware to function on the infected machine.

Propagation
The malware propagates by using the cookie session of an infected Facebook user's account to post messages to people on the person's friends list. The message posted will include some tantalizing text such as "Someboody puload a vvldeo wtlh you on utubbe you hsould see", and a link.

The message content changes as new variations are downloaded by the worm during execution.

Clicking on the link leads to an external malicious website offering a (fake) YouTube video. The user is then informed that their "Flash Player is outdated" and they are prompted to "download an update". Doing so will download the malware's executable file.

This propagation method is effective because the message is supposedly posted by a friend. A person receiving such a message is far more likely to click the included link, greatly increasing the chances of infection. This propagation method also allows the malware to spread in the MySpace social interaction website, though based on its code, Facebook is its preferred propagation site.

In addition to posting messages to other users, the worm may also propagate by putting a link on the infected user's profile, which may also lead unsuspecting users to the malicious website.

Last update 17 October 2008

 

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