Virus writers have created a Trojan which poses as London terrorist attack news footage. Infected emails harbouring the Trojan pose as a CNN Newsletter which asks recipients to ‘See attachments for unique amateur video shots’ (example below).
If executed, the malicious attachment turns infected Windows PCs into spam zombies. The as-yet unnamed Trojan attempts to obtain a list of SMTP servers that the victim's machine is configured to use and starts to use these servers to send large volumes of unsolicited mail. Email security firm MessageLabs has intercepted a handful of copies of the malware, so it's not widespread, but it does illustrate the depth virus writers are prepared to sink to in order to spread their wares.
The use of topical events to spread malware is nothing new and it wouldn't surprise us if most London bombing-themed Trojans were created. It's yet another reason to avoid any temptation to open unsolicited email attachments.