As a payload Bofra.C has an IRC-controlled backdoor that allows the creator to download and execute arbitrary programs on the compromised host.
When the worm's file is run, it copies itself to Windows System Folder with a random name ending in '32.exe' and creates a startup key for this file in the Registry:
[HKCU\Software\Microsoft\Windows\CurrentVersion\Run] "Reactor3" = "%SystemDir%\<randomname>32.exe"
%SystemDir% represents the Windows System folder name, for example C:\Windows\System32 on Windows XP systems.
To gather email addresses Bofra.C searches the Windows Address Book, files in Temporary Internet File and other files on the hard disk that have the following strings in their name:
wab pl adb tbb dbx asp php sht htm txt
Using its own SMTP engine Bofra.C sends emails to the collected addresses. Sender of the mails is spoofed and the content is randomly chosen from the following components:
funny photos :) hello hey!
Email bodies contain an HTML-formatted text with the link:
FREE ADULT VIDEO! SIGN UP NOW!
Look at my homepage with my last webcam photos!
The email does not have any attachments. The worm only sends the link which points to the infected host. The format of the link is
h**p://<infected host ip>:port/<file_to_dowload>
Bofra.C, running on the infected host, has a stripped-down web servers listening on TCP ports starting from 1638 (0x666). The only purpose of these is to serve the potential targets with the HTML page that contains the exploit as well as the worm executable that the exploit will download.
The way this propagation technique works in explained in our weblog:
The emails sent by Bofra.C contain a fake virus scanner header (X-AntiVirus:) that might get one of the following values:
scanned for viruses by AMaViS 0.2.1 (http://amavis.org/) Checked for viruses by Gordano's AntiVirus Software Checked by Dr.Web (http://www.drweb.net)
The worm avoids posting to e-mail addresses that contain certain strings, among them:
berkeley unix math bsd mit.e gnu fsf. ibm.com google kernel linux fido usenet iana ietf rfc-ed sendmail arin. ripe. isi.e isc.o secur acketst pgp tanford.e utgers.ed mozilla
As a payload Bofra.C has an IRC-controlled backdoor that allows
the creator to download and execute arbitrary programs on the
Detection for Bofra.C was published on November 9th, 2004 in the following F-Secure Anti-Virus updates:
Write-Up: Mikko Hypponen, November 9th, 2004;
Technical Details: Gergely Erdelyi, November 9th, 2004;