Locky Ransomware Replaces Dridex as the Top Email Security Threat
Locky was first identified in February 2016 and is believed to have been released by the criminal gang behind the Dridex banking malware. In fact, Locky is distributed using the infamous Necurs botnet, one of the largest botnets currently in operation. Necurs was also used to deliver Dridex malware, which was the top email security threat in Q1. Figures from Proofpoint suggest Locky has been used in 69% of email attacks involving malicious documents in Quarter 2, 2016.
Not only is Locky now the top email security threat, malicious message volume also increased significantly in quarter 2. Proofpoint charted the rise in malicious email volume and the Quarterly Threat Summary shows volume has increased by 230% since Q1, 2016.
Bear in mind that the huge rise in malicious emails occurred even though the Necurs botnet went silent in early June and Locky emails essentially stopped being delivered. However, the botnet did not remain inactive for long. By the end of June it was back with a vengeance, with huge volumes of Locky emails delivered as part of a massive new campaign.
Exploit Kits Are Mostly Delivering CryptXXX Crypto-Ransomware
While Locky may be the top email security threat, exploit kits still pose a major risk to businesses and personal computer users. The Angler exploit kit may have died a death in early June, but Neutrino has now taken over as the EK of choice. Neutrino is targeting numerous vulnerabilities and CryptXXX crypto-ransomware is the main threat. The ransomware variant only appeared in Q2, but it has fast become a major problem and the most common EK threat.
CryptXXX may now be the most prevalent EK ransomware variant in use; however, there has been an explosion in the number of ransomware variants in 2016. Since the final quarter of 2015, the number of ransomware variants has increased by a factor of between 5 and 6 according to Proofpoint. The majority of ransomware is delivered via exploit kits, although many users are directed to malicious websites via links delivered by spam email.
Fortunately, EK activity has fallen considerably since April. Angler EK activity started to decline in late April and by the start of June EK activity had dropped by around 96%. Since the end of June, EK activity has started to increase with Neutrino the main EK now in use. Fortunately, EK activity has not returned to pre April levels. So far at least.