Pierluigi Paganini March 01, 2019

Experts analyzed tools and intrusion methods used by the
China-linked cyber-espionage group Emissary Panda in attacks over the past 2 years.

This morning I wrote about a large-scale cyber attack that hit the International Civil Aviation Organization (ICAO) in November 2016, Emissary Panda was suspected to be the culprit.

Experts at Secureworks reports who investigated the incident, now reveal that the same threat actor used an array of tools and intrusion methods in attacks over the past 2 years.

The Emissary Panda APT (aka LuckyMouse, APT27, Threat Group 3390, and Bronze Union) has been active since 2010, targeted organizations worldwide, including U.S. defense contractors, financial services firms, and a national data center in Central Asia.

The group was involved in cyber espionage campaigns aimed at new generation weapons and in surveillance activities on dissidents and other civilian groups. 

The cyber espionage group leverage both readily available tools and custom malware in their operations, many tools are available for years, but in recent attacks, their code was updated.

“In 2018, CTU researchers identified evidence of BRONZE UNION leveraging tools that have been publicly available for years. However, the variants used in 2018 included updated code.” states the report published by Secureworks.

Secureworks argued that attackers are persistent, experts observed that the group usually returns to compromised networks every three months to verify its abilities to access it and that the web shells are correctly working.

In 2018, Emissary Panda was observed using an updated version of the ZxShell RAT first developed in 2006 and whom code was released in 2007. The malware includes the well-known HTran packet redirection tool and was signed with digital certificates that were signed by Hangzhou Shunwang Technology

In 2018, Emissary Panda also used a modified version of Gh0st RAT to infect multiple systems and make lateral movements.

“This Gh0st RAT sample communicated with IP address 43[.]242[.]35 [.]16 on TCP port 443, although the traffic is a custom binary protocol and not HTTPS. The malware author also modified the standard Gh0st RAT headers to obfuscate the network traffic.”

The threat actors were also observed using custom tools in attacks observed since 2016, such as SysUpdate and HyperBro.

In the arsenal of the group there is also the multi-stage malware SysUpdate, that is used exclusively by the APT group. The cyber spies delivered the threat in multiple ways, including malicious Word documents leveraging Dynamic Data Exchange (DDE), manual deployment via stolen credentials, or via a redirect from a strategic web compromise (SWC). In all the cases, attackers deliver a WinRAR self-extracting (SFX) file that installs the SysUpdate stage 1 payload, that gains persistence and downloads and executes the second stage payload, SysUpdate Main.

“SysUpdate Main employs HTTP communications and uses the hard-coded User-Agent “Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/34.0.1847.116 Safari/537.36”. It downloads a file named m.bin using the HTTP GET method and injects this file into a new svchost.exe process without saving the file to disk.” continues the analysis.

“After performing this download, SysUpdate Main reverts to its binary protocol for any additional commands from the C2 server, beaconing every three minutes.”

Experts described SysUpdate as a flexible malware that could expand its capabilities by loading new payload files.

“During complex intrusion scenarios, the threat actors leverage their proprietary tools, which offer custom functionality and lower detection rates. They appear to prefer using widely available tools and web shells to maintain access to networks over longer periods.” Secureworks concludes.

“After accessing a network, the threat actors are adept at circumventing common security controls, escalating privileges, and maintaining their access to high-value systems over long periods of time,”

Pierluigi Paganini

(SecurityAffairs – Emissary Panda, hacking)

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