Threat description




The CiaDoor backdoor is a family of backdoors generated by the C.I.A development kit. The backdoor is written in Visual Basic and compiled as p-code. It can be additionally packed with executable packers such as UPX.

The development kit allows to customize the capabilities of the server part (listening port, password, services, etc.). This method was first introduced by the Back Orifice 2000 backdoor and it allows much more flexibility to backdoors.


Manual Disinfection

To manually disinfect CiaDoor backdoor, it's enough to delete the backdoor main file from the Windows directory. The file is hidden and locked, so it cannot be directly deleted and it is not visible with the normal Windows tools. Disinfection can be done by deleting all relevant registry keys (see the Details below) and rebooting the computer or by manually renaming the file and rebooting. After the system restart the backdoor main file can be deleted.

Technical Details

When run, the backdoor copies itself to the Windows directory using configurable name, for example "Csrss.exe". After that it patches Windows Registry so that it will be run during every Windows startup.

It creates the following registry keys:

[HKLM\SOFTWARE\Microsoft\Active Setup\Installed Components\{44BBA855-CC51-11CF-AAFA-00AA00B6017B}]  "StubPath" = "%Windir%\%filename%"  "ComponentID" = %name%  "IsInstalled" = 1  "Locale" = "en"  "Version" = "4,88,55,1"   

where %filename% is the actual file in Windows directory, for example "Csrss.exe". %name% is configurable by the author, it can be for example "Runtime Process".

The backdoor can also install and modify registy keys:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run  HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices  HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run  HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\winlogon  HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run  HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices  HKCU\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows\Run   

If the system is Win9x, the backdoor also modifies files


After the system installation, the backdoor starts its services and displays a configurable fake error message.

The server part can have any of the following capabilites:

1. Copy, delete, upload, dowload, and execute files  2. Enumerate and kill processes  3. Manipulate system settings (cd-rom, keyboard, mouse)  4. Capture screenshots, audio and keystrokes  5. Shut down Windows  6. Fake MSN login screen to steal account information  7. Steal CD keys of various games and applications   

The actual server port is configurable. Example banner of the server (version 1.21) looks like this:

(__( C.I.A v1.21 - Enter Password)__)   

CiaDoor also starts FTP service for local filesystem file manipulation. The FTP service uses standard ftp port (TCP 21). The server banner looks like this:

220-  220- (___( C.I.A v1.21 Ftp Server Ready )___)  220- (___( Welcome pokermon)___)  220- (___( Coded By Alch3mist of th3 DCC )___)  220- (___( )___)  220  

CiaDoor tries to use different Web pages and e-mail accounts to notify the author that the victims are online.


F-Secure Anti-Virus detects various variants of the CiaDoor backdoor starting with the following update:

Detection Type: PC

Database: 2003-03-25_01

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