Threat description


Category: Malware
Type: Trojan
Platform: W32


Sysbug is spying trojan with backdoor capabilities that was spread on 25th of November 2003. It was sent in e-mail messages to a lot of e-mail addresses. When activated, the trojan steals certain information from an infected computer. It can also download and activate executable files on an infected computer.


Automatic action

Depending on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the suspect file, or ask you for a desired action.

More scanning & removal options

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You may also refer to the Knowledge Base on the F-Secure Community site for more information.

Contact Support

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Technical Details

Sysbug trojan was spread in private-looking e-mails that looked like that:



Re[2]: Mary   


Hello my dear Mary,  I have been thinking about you all night. I would like to  apologize for the other night when we made beautiful love and did  not use condoms. I know this was a mistake and I beg you to  forgive me.  I miss you more than anything, please call me Mary, I need you.  Do you remember when we were having wild sex in my house? I  remember it all like it was only yesterday. You said that the  pictures would not come out good, but you were very wrong, they  are great. I didn't want to show you the pictures at first, but  now I think it's time for you to see them. Please look in the  attachment and you will see what I mean.  I love you with all my heart, James.   


The '' attachment contains the trojan's executable file with 'wendynaked.jpg.exe' name. The trojan's file is packed with UPX file compressor and is 11808 bytes long.

When run by a user, the trojan installs itself to system. It copies itself to Windows folder as 'sysdeb32.exe' file and creates a startup key for itself in the Registry:

[HKLM\Software\Microsoft\Windows\CurrentVersion\Run]  "SystemDebug" = "%windir%\sysdeb32.exe"   

where %windir% is the name of Windows directory. That way the trojan is started every time when Windows starts.

Being active, the trojan collects certain information from an infected computer and uploads this info to '' website via HTTP protocol. The trojan steals the following information:

POP server name, user name and password  NNTP server name and user name  SMTP server name, account name, display name, e-mail address and organization name  RAS information  Edialer information   

Beside the above mentioned data the trojan reports the following info to '' website:

IP address  unique ID  connection speed  active time   

The trojan creates TEMP35.TXT file in the root folder of C: drive and SVC.SAV file in Windows folder. These are data files used by the trojan.

When active, the backdoor part of the trojan listens to TCP port 5555.

The trojan has the ability to download executable files and run them. The downloaded file is saved to 'c:\tmp.exe' file, which is then activated.

The trojan periodically connects to website. If it becomes widespread, it might cause a DoS (Denial of Service) attack on that server.

The trojan has a fake copyright message in its body:

/* Written By Adrey Karimov [] */   


Detection in F-Secure Anti-Virus was added on November 25th, 2003 in the following updates: Detection Type:PC

Technical Details: Alexey Podrezov, November 25th, 2003


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