Summary

When run, the backdoor copies itself to startup folder, mails the IP address of the PDA to the backdoor author and starts listening commands on a TCP port. The hacker can then connect back to the PDA via TCP port and control the PDA through the backdoor.

Brador has not been seen in the wild. It only runs on ARM-based Pocket PC devices that have Windows Mobile 2003 (Windows CE 4.2) or later.

Brador is a backdoor, not a virus. It will not spread on it's own.

Disinfection

Run the F-Secure Anti-Virus for Pocket PC delete infected files and reboot the device.

Manual disinfection

Or if you need to do it manually, delete svchost.exe from Windows\StartUp directory with the Pocket PC explorer and reboot the device.

Additional Details

When run the Brador will copy itself to Windows\StartUp directory as svchost.exe on the Pocket PC device, so that it will automatically start at each time when device boots.

The installation routine makes slight modifications to the file copied to Windows\StartUp directory. So the file will be a bit different at each boot, although this will not affect the operation of the backdoor. It is still unclear whether this is intentional or side effect of the installation routine.

Payload

When the Brador has installed itself into the system it will read the local host IP address and email that to the author.

After emailing it's IP address the backdoor opens a TCP port and start listening commands from it.

The backdoor is capable of uploading and downloading files from PDA, executing arbitrary commands and displaying messages to the PDA user.

Writeup: Mikko Hypponen, Jarno Niemela, August 6th, 2004

F-Secure Corporation