Worm:W32/Zotob.A is a clone of Worm:W32/Mytob.A that spreads using a vulnerability in Windows Plug and Play service (MS05-039).
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.
The worm is a packed PE executable file 22528 bytes long.
When run, the worm saves a copy of itself to the System directory using the name "botzor.exe" and creates a mutex named "B-O-T-Z-O-R" to ensure only one copy of the worm is run at any one time.
It then adds the following registry entries to ensure that it is started when a user logs on or the system is restarted:
The worm also adds the following registry key to diasable shared access service:
To propagate itself, the worm scans for systems vulnerable to Microsoft Windows Plug and Play service (MS05-039) through TCP/445. The exploit uses fixed offsets inside Windows 2000 version of umpnpmgr.dll. This means that only Windows 2000 systems (SP0-4) are affected. Please see the following page for detailed information on the vulnerability: http://www.microsoft.com/technet/security/Bulletin/MS05-039.mspx
To scan for vulnerable systems, Zotob creates 300 threads that connect to random IP addresses within the B-class (255.255.0.0) network of the infected system. It first tests connection to port 445 and if successful, it tries to exploit the vulnerability.
If the attack is successful, a command shell is started on the remote computer's port 8888. Through the shell port, the worm sends a FTP script which instructs the remote computer to download and execute the worm from the attacker computer using FTP.
All infected computers listen on port 33333 in order to serve out the worm to other hosts being infected. The downloaded file is saved as 'haha.exe' on disk.
Here is the summary of the ports used in attack:
The worm tries to connect to a predefined IRC channel. An attacker who knows channel password can instruct the bot to execute the following actions:
Zotob.A modifies the system hosts file to disable access to certain sites. The following hostnames are redirected to localhost IP address (127.0.0.1):
The worm also writes the following text to hosts file: