Malware Sends Stolen Cookies to Fake WordPressAPI Site

A website pretending to be a core WordPress domain was recently used to steal user cookies and hijack sessions, Sucuri security researchers warn.

The offending website is code.wordprssapi[.]com, impersonating code.wordpressapi[.]com in an attempt to trick webmasters into considering that traffic to it is legitimate. The typo in domain name makes WordPrssAPI seem like a legitimate WordPress site, and website admins might consider it an official domain, although even the legitimate site has nothing to do with WordPress.

According to Sucuri, the fake WordPrssAPI domain was observed in a recent incident, where a piece of malware was gathering cookies and sending it to this fake site. By pretending to be working with a core WordPress domain, the malicious script could work unnoticed.

Stored in the user’s browser to track their behavior, cookies are also meant to keep users logged in during the active browsing session. Without cookies, the user would have to log in every time they wanted to take an action, so as to authenticate it. Thus, users stay logged in until they either log out or the cookie expires.

The malicious code in this incident was observed excluding cookies from user agents coming from search engine crawlers, thus ensuring that all data sent to the attacker-controlled website was more likely to immediately be usable, the researchers note.

The script would ensure the data belongs to a real user and then send it to the fake domain code.wordprssapi[.]com. These cooking allow the attacker to impersonate the user and perform various actions the users has permissions to perform. This type of attack becomes extremely dangerous when it comes to administrator users.

“These types of attack are not very common because they are complex to perform and are usually time-sensitive. Most online accounts, including WordPress, will automatically log users out after a certain period of inactivity,” Sucuri notes.

Attackers have been observed before using typos to evade detection by website owners, yet webmasters can prevent falling victims to such attacks by paying close attention to the code when auditing it.

“Be careful and always check that a domain is legitimate, especially if it is involved in collecting or sending information to a third-party site. Even if it was an official WordPress domain, sending cookies is always a red flag. Cookies contain a wealth of private information that should not be shared,” Sucuri says.

The researchers note that a core file integrity check or website monitoring service could help prevent threats, especially given that attackers are getting more creative at hiding their tracks.

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