Summary
Bofra.A worm appeared on November 10th, 2004. This worm exploits an unpatched vulnerability in Internet Explorer's IFRAME handling. Unlike regular mass-mailing worms, Bofra.A does not send itself in the emails, only an HTTP link that points to the host that sent the infected email.
As a payload Bofra.A has an IRC-controlled backdoor that allows the worm's author to download and execute arbitrary programs on the compromised host.
Removal
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:
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Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.
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If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Note: You need administrative rights to change the settings.
Technical Details
The worm's body is a Windows PE executable file compressed with the MEW executable compressor and was patched by PE_Patch utility.
System Infection
When the worm's file is run, it copies itself to Windows System Folder with a random name ending in '32.exe' (for example pmbperim32.exe) and creates a startup key for this file in the Registry:
[HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "Rhino" = "%SystemDir%\[randomname]32.exe"
where "%SystemDir%" represents the Windows System folder name, for example "C:\Windows\System32\" on Windows XP systems.
Email Propagation
To gather email addresses Bofra.A 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.A sends emails to the collected addresses. Sender of the mails is spoofed and the content is randomly chosen from the following components:
Email subjects:
funny photos :) hello hey!
Email bodies contain an HTML-formatted text:
FREE ADULT VIDEO! SIGN UP NOW!
or
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
https://[infected host ip]:port/[file_to_dowload]
Bofra.A, 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 emails sent by Bofra.A 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 email addresses that contain certain strings:
avp syma icrosof msn. hotmail panda sopho borlan inpris example mydomai nodomai ruslis .gov gov. .mil foo. 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 root info samples postmaster webmaster noone nobody nothing anyone someone your you me bugs rating site contact soft no somebody privacy service help not submit feste ca gold-certs the.bat page admin icrosoft support ntivi unix bsd linux listserv certific google accoun
The worm fakes the sender's address. It uses the following list of names to compose the fake address:
john john alex michael james mike kevin david george sam andrew jose leo maria jim brian serg mary ray tom peter robert bob jane joe dan dave matt steve smith stan bill bob jack fred ted adam brent alice anna brenda claudia debby helen jerry jimmy julie linda sandra
The worm uses the following list of domain names to compose the fake sender's address:
aol.com msn.com yahoo.com hotmail.com
Backdoor
As a payload Bofra.A has an IRC-controlled backdoor that allows the worm's author to download and execute arbitrary programs on the compromised host.
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