In July, security researchers from FireEye uncovered and blocked a campaign carried out by Chinese APT10 group (aka Menupass, and Stone Panda) aimed at Japanese media sector.
Experts noticed the group since around mid-2016 when it was using PlugX, ChChes, Quasar and RedLeaves malware in targeted attacks.
The group has been active at least since 2009, in April 2017 experts from PwC UK and BAE Systems uncovered a widespread hacking campaign, tracked as Operation Cloud Hopper, targeting managed service providers (MSPs) in multiple countries worldwide.
In July 2018, FireEye observed a series of new attacks of the group leveraging spear-phishing emails using weaponized Word documents that attempt to deliver the UPPERCUT backdoor, also tracked as ANEL.
The ANEL malware was already seen in the previous attack as a beta version or release candidate.
The spear phishing emails have an unreadable content and use titles related to maritime, diplomatic, and North Korean issues. The body of the messages includes a password to use to see the password-protected document.
The analysis of the UPPERCUT samples revealed that their timestamps were overwritten and filled with zeroes. The experts pointed out the lack of visibility into the UPPERCUT 5.2.x series, but they speculated that minor versions might have been released every few months between December 2017 and May 2018.
“The compile time of loaders in the newer version(s) are not shown here since the timestamps are overwritten and filled with zeroes. We don’t have visibility into UPPERCUT 5.2.x series, but it’s possible that minor revisions were released every few months between December 2017 and May 2018.” states the report.
“Unlike previous versions, the exported function names are randomized in the latest version”
The latest version also implements another new feature, it sends an error code in the Cookie header when failing to receive the HTTP response from the command and control (C&C) server.
The malicious code support several commands such as:
The commands supported in the new version include: download and validate file; upload file to the C&C; load PE file; download, validate, execute file, and send output to C&C server; format the current timestamp; capture the desktop screenshot in PNG format and send it to C&C; execute received buffer via cmd.exe and send the output to the server.
“While APT10 consistently targets the same geolocation and industry, the malware they use is actively evolving,” FireEye concludes.
“In the newer versions of UPPERCUT, there is a significant change in the way backdoor initializes the Blowfish encryption key, which makes it harder for analysts to detect and decrypt the backdoor’s network communications. This shows that APT10 is very capable of maintaining and updating their malware,”
(Security Affairs – APT10, cyber espionage)