Russian nation-state hackers have been targeting Ukrainian users of the Signal app through phishing attacks, using social engineering tactics to exploit data security vulnerabilities. These hackers, likely tied to Russian intelligence agencies, have focused on Signal’s popularity among politicians, journalists, and activists. Their goal is to gain access to sensitive information by circumventing the app’s end-to-end encryption, primarily by manipulating victims into revealing their messages.
Google Threat Intelligence researchers warn that these methods could proliferate globally, extending to users in other regions beyond Ukraine.
One of the main techniques used in these attacks is the abuse of Signal’s linked devices feature, which allows users to synchronize their message history across multiple devices. Hackers have been sending malicious QR codes designed to link the victim’s account to a hacker’s device. This tactic gives the attacker ongoing access to the victim’s messages without the victim noticing. Google researchers caution that this type of compromise can go undetected for extended periods, increasing the risk to users.
The hackers have also disguised their malicious QR codes as legitimate Signal group invitations or device pairing instructions. In more targeted cases, these QR codes have been embedded in phishing pages disguised as specialized apps meant for Ukrainians. The Russian hacking group Sandworm, linked to the Russian military intelligence directorate, is reportedly involved in these attacks, working to link Signal accounts on devices captured in the conflict. Another threat actor, UNC5792, has used similar tactics by sending malicious group invites that redirect victims to a phishing page that links their account to the attacker’s.
Signal has responded to these findings by reinforcing its linked device feature to protect users. Meanwhile, similar tactics have been employed against other encrypted messaging services, including WhatsApp and Telegram. Microsoft recently uncovered a related campaign involving the Russian Federal Security Service, which targeted WhatsApp accounts belonging to civil society organizations and journalists using QR codes. These growing threats underscore the continued risk to encrypted communication platforms, especially in politically sensitive regions.
