Similar to the previous campaign TAG reported on, North Korean threat actors used social media sites like X (formerly Twitter) to build rapport with their targets. In one case, they carried on a months-long conversation, attempting to collaborate with a security researcher on topics of mutual interest. After initial contact via X, they moved to an encrypted messaging app such as Signal, WhatsApp or Wire. Once a relationship was developed with a targeted researcher, the threat actors sent a malicious file that contained at least one 0-day in a popular software package.

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In addition to targeting researchers with 0-day exploits, the threat actors also developed a standalone Windows tool that has the stated goal of ‘download debugging symbols from Microsoft, Google, Mozilla and Citrix symbol servers for reverse engineers.’ The source code for this tool was first published on GitHub on September 30, 2022, with several updates being released since. On the surface, this tool appears to be a useful utility for quickly and easily downloading symbol information from a number of different sources. Symbols provide additional information about a binary that can be helpful when debugging software issues or while conducting vulnerability research.

But the tool also has the ability to download and execute arbitrary code from an attacker-controlled domain. If you have downloaded or run this tool, TAG recommends taking precautions to ensure your system is in a known clean state, likely requiring a reinstall of the operating system.

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As part of our efforts to combat serious threat actors, TAG uses the results of our research to improve the safety and security of Google’s products. Upon discovery, all identified websites and domains are added to Safe Browsing to protect users from further exploitation. TAG also sends all targeted Gmail and Workspace users government-backed attacker alerts notifying them of the activity and encourages potential targets to enable Enhanced Safe Browsing for Chrome and ensure that all devices are updated.