Over the past month, thousands of websites built on the WordPress and Joomla! content management systems have been compromised to redirect users to the CryptXXX ransomware, Sucuri researchers reveal.
This mass infection campaign supposedly kicked off on June 9, but researchers observed it spiking on July 3. According to Sucuri, at least 2,000 websites were injected with malicious code, but a realistic estimation would be five times higher, because the estimate is based on data coming from the SiteCheck scanner only, which is limited.
The main characteristic of this campaign is the use of realstatistics[.]info and realstatistics[.]pro domains to redirect users to the Neutrino exploit kit (EK) landing page. Neutrino, currently the leading threat in the EK landscape, attempts to leverage Flash or PDF vulnerabilities on the target machine and drops the CryptXXX ransomware if successful.
A few days ago, Forcepoint researchers revealed that the aforementioned domains were used as Traffic Direction Systems (TDSs) in ongoing Neutrino and RIG distribution campaigns. The researchers eventually associated the domains with the two-year old Blackhat-TDS, explaining that they were used to redirect only unsuspecting users to EK’s landing page, while serving clean pages to blacklisted IP ranges (representing security vendors, search engines, and web scanning services).
What Forcepoint researchers didn’t reveal, however, was the extent of the campaign and how the attackers managed to compromise websites. Now, Sucuri explains that 60% of the affected sites are using outdated Joomla! and WordPress versions, but also say that the attackers most likely abused vulnerable components like plugins and extensions.
“When a CMS is out of date, it speaks volumes to the administration/maintenance strategies a website is employing. If a website owner is unable to keep their core up to date, we can confidently say that they are likely not keeping the extensible components up to date. And we know from our previous research that the leading vector in most CMS applications comes from third-party integrations like plugins and extensions,” the researchers say.
With thousands of compromised websites at their disposal, including some security-related destinations such as the PCI Policy Portal, the attackers can target tens of thousands of users at the same time, eventually infecting many of them with the CryptXXX ransomware. A couple of weeks ago, SentinelOne researchers revealed that CryptXXX operators made $50,000 in under three weeks on a single Bitcoin address only.
Clearly, the threat actor is determined to use the top distribution venues available, especially after it switched to Neutrino last month, immediately after Angler, the top EK for many years, disappeared from the threat landscape. CryptXXX has become the top ransomware out there and has received numerous updates over the past couple of months.
The most recent change was observed by SANS Internet Storm Center handler Brad Duncan this week, when the ransomware started using a new ransom note and a new payment site. Duncan notes that the change in the post-infect activity of CryptXXX includes the fact that it now downloads text and HTML files for the decryption instructions in the clear.
Moreover, BleepingComputer’s Lawrence Abrams reveals that the CryptXXX no longer uses a special extension for the encrypted files and that victims are now directed to a new payment site called Microsoft Decryptor. Unlike the previous payment portal, the new site no longer provides victims with the possibility to contact the admins if they have payment issues.