Twitter users targeted by Blackhole malware

Twitter users are being targeted by tweets containing malicious links that claim recipients are pictured in an online photo.

These malicious links are being spammed across the micro-blogging site, warned security firm Sophos.

The links point to Russian web pages that attempt to infect Windows PCs using the Blackhole exploit kit, the security firm said.

"If you see tweets like this, please do not click on them," said Graham Cluley, senior technology consultant at Sophos. 

"There isn't a photo of you waiting at the end of the link and the accounts spreading the messages have either been compromised by hackers or have been created by hackers with the purpose of spreading the dangerous links."

Cluley warned that if Twitter users have not properly protected their PCs, they will be putting their computers and personal data at risk by clicking on the malicious links.

Businesses and consumers can help reduce the vulnerability of computers to the Blackhole exploit kit by making sure all browsers and browser plug-ins are up to date.

The Blackhole exploit kit typically targets vulnerabilities in older versions of browsers and plug-ins such as Adobe Flash, Adobe Reader, Firefox, Google Chrome, Internet Explorer and Safari.