A newly discovered exploit kit is being disseminated via a compromised business-to-business website, Cisco Talos security researchers report.
Although the activity surrounding exploit kits (EKs) has diminished significantly following the demise of Angler in 2016, they remained a constant threat and continue to thrive, mainly because they represent a web-based platform that does not require user interaction for infection.
The recently spotted Spelevo is proof that EKs are still a threat and should be taken seriously. The threat, Cisco Talos says, illustrates many of the challenges associated with protecting against these crime kits.
On the compromised website spreading Spelevo, the attackers added only four lines of code, enough to compromise all visitors that have poor security hygiene. Multiple pages on the site were infected, including the homepage, and all of them were redirecting to the gate used for the campaign.
This “could be used as an additional tracker to ensure the victim is getting to the gate via the proper channels, a compromised website, and are not direct connects from researchers,” Talos notes.
Spelevo’s activity begins with a request for the landing page, where an initial vetting and reconnaissance of the system occur. Information collected includes operating system, web browser, and applicable plugins.
Should a vulnerable version of Adobe Flash be found, the EK attempts to exploit CVE-2018-15982. If not, a second infection path is followed, attempting to deliver an exploit for CVE-2018-8174, a use-after-free in the VBScript engine of Internet Explorer.
“It’s not surprising to find this exploit being added to multiple exploit kits, as most kits copy one another and once an exploit is available in one, the others typically are not far behind,” Talos points out.
Following system compromise, Spelevo redirects the victim to Google. Basically, the user would see a browser tab opening to load the gate, followed by the landing page, an exploit page, and then Google, which could trick some into believing they haven’t been compromised.
During the campaign, the EK was observed delivering the IcedID and Dridex Trojans, but the payloads could vary in other attacks.
Although observed only a couple of months ago, Spelevo has already gone through some changes, including a modified URL structure and some obfuscation updates in the landing and exploit pages. The threat, however, makes use of many common techniques that EKs have been employing for years.
Spelevo is being hosted on domains instead of hard coded IP addresses and its operators leverage domain shadowing for that.
“In much the same way that we see old threats like MyDoom and Stuxnet circulating on the internet today, exploit kits will be a permanent part of the threat landscape. They are still incredibly effective at leveraging existing vulnerabilities to randomly compromise victims on the internet to deliver a malicious payload,” Talos notes.
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