Not long after the first proof-of-concept Pocket PC virus was found, a real trojan program is being distributed, targeting this platform. Brador.a (or WinCE.Brador.a as defined by Symantec) is a backdoor (a utility allowing for remote administration of the infected machine) for Windows Mobile Pocket PC. It is written in ASM for ARM-processors and is 5632 bytes in size.
Brador is created to allow the master full control over the infected PDA via the port that the Trojan opens. Brador is programmed to upload and download files and execute a series of further commands. Like all backdoors, Brador cannot spread by itself: it can only arrive as an email attachment, be downloaded from the Internet or uploaded along with other data from a desktop.
After Brador is launched in creates an svchost.exe file in the /Windows/StartUp/ folder, thus gaining full control over the handheld every time it is restarted (soft reset). The program then identifies the IP address of the infected handheld and sends it to the virus coder to inform him that the handheld is connected to the Internet and that the backdoor is active. Brador then opens port 2989 and awaits further orders.
The backdoor responds to the following commands:
d - lists the directory contents
f - closes the session
g - uploads a file
m - displays MessageBox
p - downloads a file
r - executes a specified command
Symantec reports this trojan here and Kasperski is reporting it here.