IDE rule file fetched from homoglyphed domain
Summary
.cursorrules extends from a URL using a homoglyph — e.g., `raw.githubusercontent.c0m` — that serves a malicious ruleset. Casual review misses the character substitution.
Severity & confidence
Medium
Notable weakness with plausible abuse chains or partial mitigations already in place. Track, and resolve as part of your normal hardening cadence.
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)https?://[a-z0-9.-]*\b(?:githubusercoontent|raw\.githubusercontent\.c0m|g1thub)
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_000078
{
meta:
source = "jiffy-intel"
severity = "medium"
description = "Auto-generated from Jiffy Intel indicators"
strings:
$content_pattern_0 = "(?i)https?://[a-z0-9.-]*\\b(?:githubusercoontent|raw\\.githubusercontent\\.c0m|g1thub)"
condition:
$content_pattern_0
}Auto-generated from the indicators above. Adapt syntax for your detection stack before deploying.
Affected tools
| Tool | Versions | Status |
|---|---|---|
| Cursor | * | vulnerable |
| Claude Code | * | 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.
- .cursorrules (repo: fast-start-pack)IDE rulesRemoved
- .cursorrules (repo: cool-tools-kit)IDE rulesQuarantined
How to remediate
- 01Whitelist exact hostnames in URL allowlists.
- 02Scan rule file URLs for Unicode confusables.
Timeline & sources
Timeline
- First observedMar 27, 202621 days ago
- Last updatedApr 28, 2026today
- PublishedApr 4, 202613 days ago
Sources
References
OWASP 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/Jiffy Research — .cursorrules and agents.md Config Backdoors
https://blog.jiffylabs.ai/posts/cursorrules-and-agents-md-config-backdoorsScan for patterns like this
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