Mustang Panda (a.k.a. Temp.Hex, HoneyMyte, TA416 or RedDelta), a China-based advanced persistent threat (APT), has been traced to an ongoing cyberattack campaign using a formerly undocumented variation of the PlugX remote access trojan on affected workstations mostly in and around Southeast Asia. For its similarities to another PlugX (aka Korplug) variation called THOR which surfaced in July 2021, slovak cybersecurity firm ESET termed the current version Hodur.
Korplug is a proprietary virus used widely, it was initially uncovered in a 2020 investigation that looked into Chinese hackers' activities against Australian targets. Mustang Panda employs phishing lures with counterfeit papers to target European embassies, ISPs (Internet Service Providers), and research institutes in the most recent known campaign, according to cybersecurity firm ESET. "Anti-analysis measures and control-flow obfuscation are used at every level of the deployment process," the firm told.
Hodur is based on PlugX, a remote access tool that "allows remote users to steal data or take control of impacted systems without authorization. It can copy, move, rename, execute, and delete files, as well as log keystrokes and fingerprint the infected system." The infections end with the implementation of the Hodur backdoor on the infected Windows host, irrespective of the phishing lure used.
As formerly stated, the campaign begins simply, with the group phishing its targets using current events. Proofpoint identified it using a NATO diplomat's email address to send out.ZIP and.EXE files labeled "Situation at the EU Borders with Ukraine" last month. If a victim accepts the bait, a legitimate, properly signed executable prone to DLL search-order hijacking will be delivered. Russia, Greece, Cyprus, South Africa, Vietnam, Mongolia, Myanmar, and South Sudan are the countries targeted in this campaign.
ESET claims to have sampled sophisticated custom loaders as well as new Korplug (Hodur) versions still using DLL side-loading but has considerably more robust obfuscation and anti-analysis techniques across the infection chain. The side-loading custom DLL loader uses a digitally-signed genuine executable, in this case, a SmadAV file, and leverages a known flaw. Except for one, which loads the new Korplug variation, the loader's many functions are all fake.
As it is a Chinese actor with a history of pursuing higher political espionage purposes, the scope of its targeting should be rather consistent.
