The Darkleech campaign responsible for compromising thousands of websites has resurfaced, targeting Java and Adobe vulnerabilities to spread the Reveton ransomware.
Security firm FireEye reported being alerted to the latest wave of Darkleech attacks in a public blog post after its own web url was being targeted. "We were notified by several security researchers that a fireeye[.]com/careers HR link was inadvertently serving up a drive-by download exploit," read the post.
"It turns out, this attack was not targeted and it was not a watering hole attack. Instead, this campaign appears to be a recent wave of the Darkleech malware campaign, where third-party Horde/IMP Plesk Webmail servers were vulnerable to attack and used to serve up Java exploits that ultimately drop yet another ransomware named Reveton (similar to Urausy)."
Malware research engineer at FireEye Josh Gomez told V3 the attack is a development on the traditional Darkleech operation, and uses a multi-stage process to redirect users to malware-ridden websites.
"Darkleech itself is mainly responsible for getting you to the page that does the actual exploitation. Think of it as a crook who jumps out of some dark alley as you are trying to walk to the store. You are minding your own business when he pops out and says, ‘Hey, come here, go this way, this is the way to the store.' Next thing you know, you follow his lead and end up getting robbed and assaulted by masked men in that alley," he said.
"The next stage is where the actual attack takes place, systems become exploited and subsequently infected. The URL that Darkleech tries to get the victim to load is typically that of a site hosting the Blackhole Exploit Kit. The Blackhole Exploit Kit is a professional framework for automatically exploiting weaknesses in vulnerable browsers, as well as vulnerable versions of Java and Adobe software, such as Adobe Reader."
Gomez said the new attack will likely be a headache for businesses, as the criminals' infection method can circumvent many traditional cyber defences and can be used to spread a multitude of other malware when combined with tools such as the Blackhole Exploit Kit. "This type of attack can affect users and business by subverting perimeter security defences and allowing dangerous malware to enter the enterprise," he said.
"In the case of Darkleech plus Blackhole campaigns, we primarily see click-fraud Trojans (ZeroAccess), downloaders (that download other malware, such as Pony), credential-stealing banking Trojans (Zbot/Zeus) and ransomware-style malware where a user's computer can be locked and held hostage until a ‘ransom' is paid to unlock it."
The FireEye researcher said businesses should to be extra vigilant with their update cycles and reassess whether they need to run Java.
"To defend against this sort of attack, enterprises and users should maintain up-to-date versions of web browsers as well as Java and Adobe reader versions. If Java is not needed, it can be disabled to mitigate Java-based attacks. Also, having up-to-date perimeter security solutions as well as host antivirus and intrusion prevention systems on the endpoint itself can help prevent falling victim," he said.
Darkleech is a malicious module designed to target Apache (web) servers. It is already believed to have turned thousands of websites hosted on Apache into malware-spreading tools. Worse still, the tool is known to be available on numerous cyber black markets for as little as $1,000.