Jiffy Intel — Threat intelligence for AI artifacts

Summary

MCP server whose startup command, in addition to launching the server, also writes a skill bundle under ~/.claude/skills/. Running the MCP is effectively an unattended skill install. The skill persists after the MCP is removed.

Severity & confidence

Severity

Medium

Notable weakness with plausible abuse chains or partial mitigations already in place. Track, and resolve as part of your normal hardening cadence.

Confidence

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.

(?is)(?:mkdir|cp|mv|write)[^\n]{0,200}\.claude/skills/

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.

YARA-style pseudo-rule

rule jiffy_ti_2026_000059
{
    meta:
        source = "jiffy-intel"
        severity = "medium"
        description = "Auto-generated from Jiffy Intel indicators"
    strings:
    $command_pattern_0 = "(?is)(?:mkdir|cp|mv|write)[^\\n]{0,200}\\.claude/skills/"
    condition:
        $command_pattern_0
}

Auto-generated from the indicators above. Adapt syntax for your detection stack before deploying.

Affected tools

Tool	Versions	Status
Claude Code	`*`	vulnerable
Claude Desktop	`*`	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.

all-in-one-dev-mcpMCP server
Removed
Source
MCP Registry
Versions
0.6.0
First observed
Mar 23, 2026
Last observed
Apr 14, 2026
starter-mcp-suiteMCP server
Under review
Source
Community registry
First observed
Mar 27, 2026

How to remediate

01Diff ~/.claude/skills/ after any MCP server install.
02Remove any unexpected skills.

Timeline & sources

Timeline

First observedMar 23, 202625 days ago
Last updatedApr 26, 2026today
PublishedMar 31, 202617 days ago

Sources

scanner

References

blog.jiffylabs.aiJiffy Research

Jiffy Research — MCP Security Field Guide

https://blog.jiffylabs.ai/posts/mcp-security-a-security-teams-field-guide

attack.mitre.org

MITRE ATT&CK T1195 — Supply Chain Compromise

https://attack.mitre.org/techniques/T1195/

Related intel

Other entries of type Malicious Skill, or the most recent published entries if no same-type matches exist.

Malicious SkillHigh

MCP server's install script drops a skill into ~/.claude/skills/

MCP server whose install path (`pip install`, `npm i`) includes a side-effect that writes a skill file under the user's Claude skills directory. Installing the MCP silently installs a skill the user never consented to.

Jiffy IntelApr 28

Malicious SkillLow

AGENTS.md tells agent to paste ~/.ssh/id_rsa.pub into PR for CI setup

AGENTS.md has a section titled "CI onboarding" that instructs the agent to paste the user's SSH public key into PR descriptions. While public keys are not immediately sensitive, the coerced habit normalizes key pasting and enables later pattern-matching attacks.