WhatsApp is urging its global users to update their app after fixing a serious remote code execution (RCE) vulnerability which was being exploited in a highly targeted attack, potentially by a nation state.
The Facebook-owned mobile comms giant, which has over 1.5 billion users, rolled out a fix on Friday for the buffer overflow vulnerability in WhatsApp VOIP stack. It claimed the flaw allowed RCE “via specially crafted series of SRTCP packets sent to a target phone number.”
In effect, this means a user could be infected with the spyware payload simply by being phoned by the attacker. They don’t even have to pick up.
“The issue affects WhatsApp for Android prior to v2.19.134, WhatsApp Business for Android prior to v2.19.44, WhatsApp for iOS prior to v2.19.51, WhatsApp Business for iOS prior to v2.19.51, WhatsApp for Windows Phone prior to v2.18.348, and WhatsApp for Tizen prior to v2.18.15,” a technical note revealed.
WhatsApp’s own security team is said to have found the bug, although it has been reported that it was initially discovered and monetized by notorious Israeli firm NSO Group, whose Pegasus spyware has been sold to governments in the past to help them monitor individuals.
The firm refused to name who it suspected, saying only that it was the work of an “advanced cyber actor,” that attacks exploiting the flaw had targeted a “select number” of users, and that it bore “all the hallmarks” of a private firm that works with governments to deliver spyware targeting mobiles.
“WhatsApp encourages people to upgrade to the latest version of our app, as well as keep their mobile operating system up-to-date, to protect against potential targeted exploits designed to compromise information stored on mobile devices,” WhatsApp said in a statement sent to Infosecurity.
For its part, NSO Group reiterated in reports that its wares are only licensed to governments for the purpose of fighting crime and terror.
Chris Boyd, Malware Intelligence Analyst at Malwarebytes, argued the findings were “enormously worrying for anyone using WhatsApp on a phone alongside sensitive information.”
“The really impressive thing here is that the WhatsApp team discovered this attack at all, given no click to install is required,” he added.
WhatsApp has briefed NGOs to share any useful information, presumably to protect citizens from countries that may have been affected, and it has informed US law enforcers.