Preface: New Linux malware silently conducting the attack. The FBI and NSA issue joint security alert.

Official announcement – https://media.defense.gov/2020/Aug/13/2002476465/-1/-1/0/CSA_DROVORUB_RUSSIAN_GRU_MALWARE_AUG_2020.PDF

Remedy: To prevent attacks, the agency recommends that US organizations update any Linux system to a version running kernel version 3.7 or later, “in order to take full advantage of kernel signing enforcement,” a security feature that would prevent APT28 hackers from installing Drovorub’s rootkit.

Reference: On older versions of Linux, two buffers allocated next to each other on the heap could result in the first buffer overwriting the second buffer’s metadata. By setting the in-use bit to zero of the second buffer and setting the length to a small negative value which allows null bytes to be copied, when the program calls free() on the first buffer it will attempt to merge these two buffers into a single buffer.

Impact: Heap overflows to gain arbitrary code execution.

Headline News: https://www.zdnet.com/article/fbi-and-nsa-expose-new-linux-malware-drovorub-used-by-russian-state-hackers/?ftag=TREc64629f&bhid=22308921349725635516834735786487&mid=12982564&cid=717383279