Skill Trust Decision
VLAN Linux Client Skill
Skill instructs users to pipe a remote script from an unverified source into bash with SSL verification disabled (-k flag), enabling trivial man-in-the-middle attack and arbitrary code execution on the target system.
Most direct threat evidence
Critical Supply Chain
Remote script piped to bash without integrity verification The skill's primary installation method is 'curl -kfsSL http://dl.vlan.cn/vlan2.0/linux/install.sh | sh'. This fetches and executes arbitrary code from a remote HTTP(S) endpoint with no checksum, GPG signature, or content inspection. An attacker who intercepts the request (especially with -k disabling cert validation) can inject arbitrary code running as root.
SKILL.md:17 Why this conclusion was reached
2/4 dimensions flagged Pass
Declared vs actual capability
Declared resources and inferred behavior are broadly aligned.
Block
Hidden execution and egress
2 high-risk artifacts or egress signals were extracted.
Block
Attack chain and severe findings
The report includes 4 attack-chain steps and 3 severe findings.
Review
Dependencies and supply chain hygiene
Dependency information is incomplete, so supply-chain confidence stays limited.
Attack Chain
01
Attacker performs MITM on network path to dl.vlan.cn or compromises the domain
delivery · SKILL.md:17
02
Attacker serves a malicious install.sh script instead of the legitimate one
exploitation · SKILL.md:17
03
User executes 'curl -kfsSL http://dl.vlan.cn/vlan2.0/linux/install.sh | sh' — malicious script runs as root
Escalation · SKILL.md:17
04
Attacker gains full root access: backdoor installation, credential theft, persistence, lateral movement
Impact · SKILL.md:17
What drove the risk score up
Remote script piped to shell +40
SKILL.md documents 'curl -kfsSL http://dl.vlan.cn/vlan2.0/linux/install.sh | sh' as the primary installation method — no checksum, no GPG verification, arbitrary code execution
SSL verification disabled (-k flag) +20
The -k flag disables SSL certificate verification, making the curl|sh chain trivially interceptable via MITM, compounding the remote execution risk
Destructive command in documentation +10
SKILL.md line 193 references 'rm -rf /' — a destructive command; this could be accidental but adds to the concerning pattern
Most important evidence
Critical Supply Chain
Remote script piped to bash without integrity verification
The skill's primary installation method is 'curl -kfsSL http://dl.vlan.cn/vlan2.0/linux/install.sh | sh'. This fetches and executes arbitrary code from a remote HTTP(S) endpoint with no checksum, GPG signature, or content inspection. An attacker who intercepts the request (especially with -k disabling cert validation) can inject arbitrary code running as root.
SKILL.md:17 Remove the curl|sh installation method entirely. If installation guidance is needed, provide distribution-package install commands (apt, yum, dnf) or direct the user to download a binary with a published checksum and GPG signature.
Critical Supply Chain
SSL certificate verification disabled in installation command
The -k flag in curl disables SSL certificate verification. Combined with piping to sh, this creates a trivially exploitable MITM + RCE chain. An attacker on the network path can serve a malicious install script that compromises the system.
SKILL.md:17 Remove the -k flag. Use HTTPS with proper certificate validation and add SHA256/checksum verification of the downloaded artifact before execution.
High Credential Theft
Encourages passing passwords as plaintext command-line arguments
The skill documents 'vlancli login <username> <password>' which exposes credentials in process arguments (visible in ps, shell history, and /proc). The 'recommended' login code method is better but the password method is still presented as a valid option.
SKILL.md:26 Remove the password-as-argument login example entirely. Only document interactive or environment-variable-based credential passing methods.
Medium Doc Mismatch
Dangerous shell command reference in documentation body
SKILL.md line 193 contains 'rm -rf /' — a destructive filesystem operation. While this is likely a documentation artifact or mistake, it is extremely dangerous if the LLM reproduces it verbatim in responses.
SKILL.md:193 Remove or correct the 'rm -rf /' reference. Use specific, safe path examples (e.g., 'sudo rm -rf /usr/local/vlan') as shown elsewhere in the same document.
Declared capability vs actual capability
No capability matrix was produced.
Suspicious artifacts and egress
Critical Dangerous Command
curl -kfsSL http://dl.vlan.cn/vlan2.0/linux/install.sh | sh README.md:17
Critical Dangerous Command
rm -rf / SKILL.md:193
Medium External URL
http://dl.vlan.cn/vlan2.0/linux/install.sh README.md:17
Medium External URL
https://www.vlan.cn/guide/linux-client README.md:56
Medium External URL
https://www.vlan.cn README.md:57
Dependencies and supply chain
There are no structured dependency warnings.
File composition
2 files · 257 lines
Markdown 2 files · 257 lines
Files of concern · 2
SKILL.md Remote script piped to bash without integrity verification · SSL certificate verification disabled in installation command · Encourages passing passwords as plaintext command-line arguments · Dangerous shell command reference in documentation body · rm -rf /
README.md curl -kfsSL http://dl.vlan.cn/vlan2.0/linux/install.sh | sh · http://dl.vlan.cn/vlan2.0/linux/install.sh · https://www.vlan.cn/guide/linux-client · https://www.vlan.cn
Security positives
No executable code/scripts present in the skill — pure documentation only
Skill does not declare any allowed tools beyond documented CLI commands
No environment variable access, no file writes, no network calls from skill code
The skill correctly recommends login-code authentication over password-in-command