c2-domain-fronting
Domain fronting and CDN abuse for C2 concealment — CloudFront, Azure CDN, Fastly setup, TLS SNI vs Host header technique, CDN-based redirectors, and integration with Cobalt Strike and Sliver.
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Critical
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tessl review fix ./packages/decepticon/decepticon/skills/standard/post-exploit/c2-domain-fronting/SKILL.mdSecurity
4 findings: 2 critical severity, 1 high severity, 1 medium severity. Installing this skill is not recommended: please review these findings carefully if you do intend to do so.
E005: Suspicious download URL detected in skill instructions.
What this means
Detected a suspicious URL in the skill instructions that could lead the agent to download and execute malicious scripts or binaries. This includes links to executables from untrusted sources, typosquatting of official packages, URL shorteners that obscure the destination, and personal file hosting services.
Why it was flagged
These URLs include multiple GitHub repositories and tools explicitly referenced in a domain‑fronting / C2 skill (downloadable offensive tooling and fronting helpers), making them suspicious as potential malware distribution sources.
E006: Malicious code pattern detected in skill scripts.
What this means
Detected high-risk code patterns in the skill content — including its prompts, tool definitions, and resources — such as data exfiltration, backdoors, remote code execution, credential theft, system compromise, supply chain attacks, and obfuscation techniques.
Why it was flagged
The document explicitly provides step-by-step instructions to establish covert command-and-control channels (domain fronting, CDN redirectors), configure Cobalt Strike/Sliver implants/listeners, and proxy traffic to an attacker-controlled origin — clear intent to create and hide backdoors/C2 infrastructure.
W007: Insecure credential handling detected in skill instructions.
What this means
The skill handles credentials insecurely by requiring the agent to include secret values verbatim in its generated output. This exposes credentials in the agent’s context and conversation history, creating a risk of data exfiltration.
Why it was flagged
The prompt includes curl commands that require embedding API credentials (e.g., "Fastly-Key: <API_TOKEN>") directly into request headers/CLI invocations, which would force the LLM to handle or output secret values verbatim.
W013: Attempt to modify system services in skill instructions.
What this means
The skill prompts the agent to compromise the security or integrity of the user’s machine by modifying system-level services or configurations, such as obtaining elevated privileges, altering startup scripts, or changing system-wide settings.
Why it was flagged
The skill includes explicit instructions to modify system-level configuration (/etc/nginx, /etc/letsencrypt) and to start a listener on privileged port 443, actions that require elevated privileges and change the host machine's state.
- Repository
- PurpleAILAB/Decepticon
- Commit
e34afba
- Audited
- Security analysis
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