Suspected APT-C-00 Delivers Havoc Trojan

SUMMARY :

A recent analysis of a suspicious trojan loader reveals similarities to the APT-C-00 (Ocean Lotus) group, a government-backed hacker organization targeting East Asian companies and government agencies. The sample, a DLL file with excellent evasion capabilities, uses hash algorithms to dynamically obtain API functions. It creates a mutex for single-instance execution, validates command-line parameters, adds itself to the registry for persistence, and sets up a VEH exception handler. The loader employs module hollowing to replace code in certmgr.dll with shellcode that reflectively loads the Havoc RAT. The tactics and development environment align with Ocean Lotus' known techniques, including the use of Mingw-w64 and similar initialization processes.

OPENCTI LABELS :

apt,process hollowing,trojan,persistence,dll sideloading,east asia,havoc rat


AI COMMENTARY :

1. The Suspected APT-C-00 Havoc Trojan Incident

In a recent threat intelligence report titled “Suspected APT-C-00 Delivers Havoc Trojan,” researchers uncovered a sophisticated trojan loader that bears hallmarks of the government-backed Ocean Lotus group known as APT-C-00. This movie-style infiltration centers on a malicious DLL file exhibiting advanced evasion techniques. Analysts noted that the loader was designed to rendezvous with its command-and-control infrastructure only after ensuring it could operate under the cover of stealth. By dynamically resolving required API functions at runtime using hash algorithms, the loader avoided static indicators that might alert security tools to its presence.

2. DLL Loader Mechanics and Evasion Strategies

The sample’s core is a Windows DLL employing process hollowing and DLL sideloading to mask its true intent. Initially, the loader creates a named mutex to enforce single-instance execution and validate its command-line parameters. It then writes itself into the user’s registry for persistence and registers a vectored exception handler (VEH) to intercept and manipulate exceptions for further control flow obfuscation. These combined tactics effectively hinder behavioral monitoring and complicate reverse-engineering efforts, highlighting the group’s investment in robust malware development.

3. Persistence, Registry Manipulation, and VEH Exploitation

Beyond simple autorun entries, the loader modifies multiple registry keys to guarantee execution after system restarts and user logins. This approach ensures that even if one persistence mechanism is removed, alternative entries will trigger subsequent runs. The implementation of a VEH exception handler further allows the loader to catch illegal instructions or memory access violations as covert triggers for stage-loading the Havoc remote access trojan. Security teams should inspect unconventional exception registrations when hunting for evasive threats.

4. Module Hollowing and Reflective Loading of Havoc RAT

After establishing persistence, the loader applies module hollowing to a trusted Windows component—certmgr.dll. By unmapping the legitimate code section and injecting shellcode, the sample repurposes the DLL’s execution context to reflectively load the Havoc RAT payload. This technique avoids dropping executable files to disk and takes advantage of Windows loader trust chains. Once Havoc is active in memory, it can conduct reconnaissance and data exfiltration at the behest of APT-C-00 operators.

5. Attribution to APT-C-00 and East Asia Targeting

Analysis of the loader’s development environment reveals the use of Mingw-w64 compilers and initialization routines consistent with prior Ocean Lotus toolsets. The group’s history of targeting East Asian companies and government agencies aligns with the observed attack patterns. Code similarities with previous samples, combined with matching C2 infrastructure and shared mutex naming conventions, reinforce the attribution to APT-C-00. Organizations operating in the Asia-Pacific region should heighten vigilance for any anomalies in DLL loading and registry behavior.

6. Defensive Measures and Mitigation Strategies

To counter threats like the Havoc Trojan, defenders must implement layered security controls. Monitoring for unusual API resolution patterns and hashing operations can uncover dynamic imports. Continuous enumeration of registry autorun keys and vectored exception registrations helps identify clandestine persistence. Deploying memory-integrity protections and application control policies can block module hollowing techniques, while endpoint detection solutions with behavioral analysis capabilities can detect reflective payload loading. By combining threat intelligence on apt activity with proactive logging and response procedures, organizations can mitigate the risks posed by sophisticated trojans and government-backed adversaries.


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Suspected APT-C-00 Delivers Havoc Trojan