Sucuri observed hackers compromising around 15,000 websites as part of a huge black hat SEO campaign in order to redirect visitors to fake Q&A discussion boards.
“Our research team has tracked a surge in WordPress malware redirecting website visitors to fake Q&A sites via ois[.]is. These malicious redirects appear to be designed to increase the authority of the attacker’s sites for search engines”, Sucuri
Fake Q&A Site Promoted By This Campaign
In this case, attackers are found to be promoting a handful of fake low-quality Q&A sites. Malicious SEO redirection is considered malware because they are made to hijack a website and abuse its resources (especially website traffic and rankings).
Attackers frequently advertise spam for pharmaceutical companies, essay writing services, imitation designer products, or in this case, fake Q&A websites.
Given that even a brief operation on the first page of Google Search would cause several infections, it is likely that the campaign prepares these websites for use as malware droppers or phishing sites in the future.
Particularly, based on the presence of the “ads.txt” file on the landing pages, another possibility is that their owners are trying to increase traffic in order to commit ad fraud.
Reports say WordPress core files are the most frequently impacted, although this malware has also been reported to infect malicious.php files created by unrelated malware campaigns.
The Top 10 Most Commonly Infected Files
Researchers say, the attackers also drop their own PHP files on the targeted site, using random or pseudo-legitimate file names like ‘wp-logln.php.
The malicious code found in the infected or injected files checks to see if website visitors are signed into WordPress; if not, it sends them to the URL https://ois.is/images/logo-6[.]png.
In order to make it appear as though the websites are popular and to improve their ranking in the search results, using a Google search click URL is likely to raise performance metrics on the URLs in the Google Index. Also, redirecting through Google search click URLs makes the traffic looks more legitimate, bypassing some security software.
Researchers noticed attackers rotating the websites that they redirect to. Therefore they identified the following redirect destinations:
Those interested can find the complete list of 1,137 entries.
Sucuri was unable to determine how the domains utilized for redirections were compromised by the threat actors. It most likely occurs, though, through the use of a vulnerable plugin or brute-forcing the WordPress admin password.
Therefore, it is advised that all WordPress plugins and website CMS be updated to the most recent version and that two-factor authentication (2FA) be enabled for admin accounts.