Criminals target Discord to spread malware

Cyber criminals are abusing Discord to host, spread, and control malware which targets the users of this chat service, according to new research.

According to security researchers at Sophos, the abuse of Discord has increased in popularity since last year, as 140 times more URLs hosting malware were blocked in the past two months, compared with the same period in 2020. Researchers said Discord hosts 4% of all TLS-protected malware downloads they have detected.

In the second quarter, researchers detected 17,000 unique URLs in Discord’s CDN pointing to malware. This excludes malware not hosted within Discord that leverages Discord’s application interfaces in various ways. More than 4,700 of those URLs, which point to a malicious Windows .exe file, remained active.

Researchers said the malware is often disguised as gaming-related tools and cheats. Common “cheats” seen by researchers included modifications that allowed players to disable an opponent or to access premium features for free – usually for a popular online game, such as Minecraft, Fortnite, Roblox, or Grand Theft Auto. The researchers also found a lure that offered gamers the chance to test a game in development.

Among the most prevalent threats in Discord are information stealers. Researchers said over 10% of the malware researchers found on Discord belonged to the “Bladabindi” family of information-stealing backdoors. Researchers also found password-hijacking malware, including Discord security token “loggers” built to steal Discord accounts.

Researchers also found repurposed ransomware, backdoors, Android malware packages, and more. The analyzed files included several types of Windows ransomware that block access to data without making a ransom demand or offering victims a decryption key.

At a technical level, the researchers found some malware using the Application Programming Interface (APIs) of Discord “chatbots” to covertly communicate with and receive instructions from their command server. They also uncovered files that claim to install cracked versions of popular commercial software, such as Adobe Photoshop, and tools that claim to give the user access to the paid features of Discord Nitro, the service's premium edition.

Sean Gallagher, a senior threat researcher at Sophos said Discord provided a persistent, highly-available, global distribution network for malware operators, as well as a messaging system that these operators can adapt into command-and-control channels for their malware – in much the same way attackers have used Internet Relay Chat and Telegram.

“Discord’s vast user base also provides an ideal environment for stealing personal information and credentials through social engineering,” Gallagher said.

“Discord users, whoever they are and whatever they use the platform for, should remain vigilant to the threat of malicious content that’s lurking within the service and not just leave it to the Discord platform to identify and remove suspicious files. In addition, IT security teams should never consider any traffic from an online cloud service as inherently ‘safe’ based on the trusted nature or legitimacy of the service itself. Adversaries could be hiding anywhere.”