There are no common symptoms associated with this threat - links are activated within IFrames while viewing web content on maliciously modified pages. Alert notifications from installed antivirus software may be the only symptoms.
What to do now
To detect and remove this threat and other malicious software that may be installed on your computer, run a full-system scan with an appropriate, up-to-date, security solution. The following Microsoft products detect and remove this threat:
If this malware was discovered on a web server, it is recommended that you chance your FTP account details for the related web storage, as the presence of this malware is probable indication of an account compromise.
Downloads arbitrary files
When Trojan:JS/Iframe.BK is run, it inserts a hidden IFrame that points to a psuedo-random web address, for example "<pseudo random string>.dns-stuff.com". During our investigation of this malware, the requested addresses were unreachable.
This trojan script affects files stored on a web server and could be indicative of an FTP account compromise.