🗂️ Trace Protocol Case File: 3CX Supply Chain Attack (2023)
Not a forensic analysis — an educational overview for defenders and researchers.
📌 Case Metadata
Case ID: TP-2023-GLOB-SUPPLY3CX
Focus: Software Supply Chain Compromise via Trusted Application
Region(s): Global (primary impact in Europe and North America)
Victim Demographic: Businesses using 3CX VoIP desktop app
Threat Actor Type: State-Aligned APT (North Korea, Lazarus Group)
TL;DR
In 2023, the 3CX desktop VoIP app was compromised via a poisoned software build pipeline.
North Korea-linked threat actors inserted a malicious DLL through tampered developer libraries, resulting in a signed, trusted application distributing malware via DLL sideloading.
The breach illustrates the dangers of post-build supply chain tampering.
🧑🔬 What Happened
Lazarus Group — a North Korean state-aligned threat actor — infiltrated the 3CX development environment and introduced malicious code into the Electron-based desktop installer.
The compromised application was digitally signed and distributed via 3CX’s official update channel, delivering malware to thousands of endpoints with minimal detection.
🗓️ Attack Timeline
Feb 2023: Initial compromise of 3CX dev pipeline
Mar 2023: Malicious installers released via official 3CX updates
Mar 29: CrowdStrike and SentinelOne detect suspicious sideloading activity
Apr 2023: 3CX confirms breach; CISA and CSIRTs issue public advisories
🔬 Digital Forensics
Initial Access
Lazarus first compromised a financial software vendor (X_Trader) used by 3CX developers
A trojanised library was installed on dev endpoints, poisoning downstream build artifacts
Tooling & TTPs
DLL sideloading via
ffmpeg.dllandd3dcompiler_47.dllFinal-stage malware: ICONIC Stealer, harvesting browser data
Select targets received Gopuram — a Lazarus remote access tool
Persistence Techniques
No registry or service persistence used
Relied on execution within the trusted context of a digitally signed Electron app
Key Indicators of Compromise
Hash mismatches in
ffmpeg.dllC2 beaconing to domains like
msedgeupdater.comAnomalous behaviour in Electron-based apps with signed binaries
⚔️ Behaviour & Kill Chain
Motivation
Lazarus aimed to gain espionage-grade access to 3CX’s downstream customers, especially in finance and telecom sectors.
Attack Flow
Initial Access (X_Trader) → Build Environment Poisoning → Signed App Distribution → DLL Sideloading → Malware Deployment
MITRE ATT&CK Techniques
T1195.002– Compromise Software Dependencies & Dev ToolsT1554– Compromise Client Software BinaryT1055.001– DLL SideloadingT1083– File and Directory DiscoveryT1113– Screen CaptureT1555.003– Credential Theft: Web BrowsersT1219– Remote Access Software
💥 Impact
Compromised application deployed to thousands of enterprise systems globally
C2 activity observed in dozens of countries, with selective secondary payloads
Iconic Stealer and Gopuram RAT used for credential harvesting and remote control
Strategic Impact
Reaffirms Lazarus Group’s ability to compromise entire sectors through upstream build systems.
Reputational Effect
Severely damaged 3CX’s brand and triggered scrutiny across the Electron app ecosystem.
🔐 Key Lessons for Defenders
Immediate Wins
Validate third-party binaries — even if signed
Monitor for unexpected DLL loads inside known apps
Block C2 infrastructure tied to Lazarus campaigns
Hardening Over Time
Implement reproducible builds and developer integrity monitoring
Use secure enclaves or CI/CD isolation for high-risk build environments
Adopt and validate Software Bills of Materials (SBOMs)
People & Process
Train developers on build trust and dependency hygiene
Coordinate response across vendor-client ecosystems
Integrate supply chain attack vectors into threat modelling exercises
🧭 Final Thought
Signed doesn’t mean safe.
The 3CX breach is a textbook case of invisible malware hitching a ride inside trusted update channels.
Supply chain trust must be earned, checked, and continuously re-verified.
📎 References
