Skill "update channel" fetches from mutable S3 bucket without signature
Summary
Skills that implement an auto-update by fetching a manifest from a public S3 bucket without signature verification. The bucket ACL has historically been misconfigured on at least two occasions, allowing third-party writes. This is a pre-staged supply-chain compromise waiting for an ACL drift.
Severity & confidence
High
Credible abuse path with meaningful impact on confidentiality, integrity, or availability. Remediate on a short timeline; do not wait for the next sprint cycle.
Confirmed
Observed directly by Jiffy scanners or validated by multiple independent sources. Indicators are reliable enough to drive automated action.
Indicators
Observed patterns and artifacts associated with this entry. Each indicator can be copied into your detection stack or SIEM.
(?i)(?:self[_-]?update|check[_-]?updates?|auto[_-]?update)\s*(?:=|:).{0,120}s3\.amazonaws\.com
Detection rule
A YARA-style pseudo-rule auto-generated from the indicators above. Useful as a starting point — adapt the syntax for your target detection platform.
rule jiffy_ti_2026_000021
{
meta:
source = "jiffy-intel"
severity = "high"
description = "Auto-generated from Jiffy Intel indicators"
strings:
$content_pattern_0 = "(?i)(?:self[_-]?update|check[_-]?updates?|auto[_-]?update)\\s*(?:=|:).{0,120}s3\\.amazonaws\\.com"
condition:
$content_pattern_0
}Auto-generated from the indicators above. Adapt syntax for your detection stack before deploying.
Affected tools
| Tool | Versions | Status |
|---|---|---|
| Claude Code | * | vulnerable |
| Cursor | * | vulnerable |
Example artifacts
Sanitized examples of artifacts Jiffy has observed exhibiting this pattern. Publisher handles are redacted; version ranges and status reflect the most recent scan.
- auto-refresh-skillSkillStill live
Maintainer unresponsive; manifest still unsigned.
- release-channel-skillSkillUnder review
How to remediate
- 01Require signed manifests for any skill self-update.
- 02Reject plain HTTPS fetches of mutable artifacts without a checksum check.
Timeline & sources
Timeline
- First observedFeb 16, 20262 months ago
- Last updatedApr 14, 20263 days ago
- PublishedMar 3, 20261 month ago
Sources
References
Jiffy Research — The AI Artifact Supply Chain
https://blog.jiffylabs.ai/posts/the-ai-artifact-supply-chainOWASP LLM-03: Supply Chain (2026)
https://genai.owasp.org/llmrisk/llm-03-2026/MITRE ATT&CK T1195 — Supply Chain Compromise
https://attack.mitre.org/techniques/T1195/Scan for patterns like this
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