A vulnerability found in Facebook Messenger would allow an attacker to change a conversation thread in both the Facebook Online Chat & Messenger App.
By abusing the vulnerability, it’s possible to essentially hijack the communications, modifying or removing any sent message, photo, file, link and much more. Check Point, which discovered the flaw, pointed out that given the fact that users rely on Facebook for personal and business-related communications, this kind of malicious power could have long-ranging consequences.
For instance, malicious users can manipulate message history as part of fraud campaigns, changing the history of a conversation to claim he had reached a falsified agreement with the victim, or simply change its terms. Hackers could also tamper with, alter or hide important information in Facebook chat communications which can have legal repercussions. These chats can be admitted as evidence in legal investigations and this vulnerability opens the door for an attacker to hide evidence of a crime or even incriminate an innocent person.
Or, the vulnerability can be used as a malware distribution vehicle. An attacker can change a legitimate link or file into a malicious one, and easily persuade the user to open it. The attacker can use this method later on to update the link to contain the latest C&C address, and keep the phishing scheme up to date.
“By exploiting this vulnerability, cybercriminals could change a whole chat thread without the victim realizing. What’s worse, the hacker could implement automation techniques to continually outsmart security measures for long-term chat alterations,” said Oded Vanunu, head of products vulnerability research at Check Point.
Check Point said that Facebook has fixed the flaw following Check Point’s responsible disclosure, so users should update immediately.
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