Threat Advisory

China APT UNC5174 Hijacks Discord API as Covert C2 Channel to Evade Detection and Conduct Espionage

Threat: Malware Campaign
Threat Actor Name: UNC5174
Threat Actor Type: State-Sponsored
Targeted Region: Global
Threat Actor Region: China
Targeted Sector: Government, Critical Infrastructure
Criticality: High

EXECUTIVE SUMMARY:

A newly discovered Discord-based backdoor designed to maintain long-term access to compromised systems with stealth and low detection probability. Instead of relying on conventional command-and-control servers, the threat actors leveraged Discord, a widely trusted communication platform, to camouflage malicious traffic within normal user activity. This strategy allows remote control to appear legitimate, evading many behavioral and network-based security filters. The malware was found to be deployed after an earlier compromise, acting as a secondary persistence mechanism to ensure continued access even if the initial entry point was detected and removed. This evolution from earlier backdoors toward more covert Discord-integrated implants demonstrates a growing trend where adversaries weaponize trusted platforms to minimize forensic traceability. With the malware acting as a lightweight but fully functional control channel, defenders face greater challenges in distinguishing authentic platform communication from covert attacker activity.

The malware is built on the Discord API using a Golang-based bot framework and operates as a command-responsive backdoor. Encrypted configuration values such as tokens and channel identifiers are embedded directly into the binary, decrypted at runtime, and then used to establish communication with the attacker-controlled Discord space. The bot continuously monitors incoming messages, and each message acts as an execution trigger. When a command is issued, the malware interprets it, executes it on the infected device, captures output results into a temporary file, transmits them back through Discord, and cleans traces by deleting the file immediately after transmission. The malware supports arbitrary command execution, file uploads, downloads, and system information retrieval, granting full attacker interaction with minimal coding complexity. Despite its simplicity, detection coverage was shown to be extremely low, making the tool particularly effective for stealthy post-exploitation management. By embedding itself within an everyday communication platform, it bypasses infrastructure-based detection controls and seamlessly blends into network traffic.

This finding reinforces the growing trend of adversaries adopting legitimate communication platforms as hidden command-and-control channels. By using Discord to manage infected devices, the attackers effectively removed the need for dedicated servers, encryption layers, or proxy networks, significantly lowering detection opportunities for defenders. This also highlights how modern threat actors increasingly prioritize stealth over complexity, using small codebases and publicly available libraries to produce malware that is both agile and difficult to detect. For defense teams, this presents a critical challenge: filtering legitimate platform usage from malicious traffic without disrupting normal communication workflows. Enhanced monitoring of outbound traffic patterns, stricter application controls, sandbox analysis of unknown executables, and ongoing behavioral detection improvements are necessary to counter this approach. The emergence of such Discord-based backdoors demonstrates how attackers can exploit common digital ecosystems to maintain persistence for extended periods, underlining the need for advanced threat-hunting capabilities and proactive security measures.

THREAT PROFILE:

Tactic Technique ID Technique Sub-Technique
Execution T1059.004 Command and Scripting Interpreter Unix Shell
Defense Evasion T1027 Obfuscated Files or Information
Credential Access T1552.001 Unsecured Credentials Credentials in Files
Discovery T1082 System Information Discovery
Collection T1119 Automated Collection
Exfiltration T1041 Exfiltration Over C2 Channel
Impact T1490 Inhibit System Recovery

MBC MAPPING:

Objective Behaviour ID Behaviour
Persistence F0012 Registry Run Keys / Startup Folder
Defense Evasion F0005 Hidden Files and Directories
E1027 Obfuscated Files or Information
Anti-Behavioral Analysis B0001 Debugger Detection
Collection F0002 Keylogging
E1113 Screen Capture

REFERENCES:

The following reports contain further technical details:

https://securityonline.info/china-apt-unc5174-hijacks-discord-api-as-covert-c2-channel-to-evade-detection-and-conduct-espionage/

https://asec.ahnlab.com/en/91419/

crossmenu