Jiffy Intel — Threat intelligence for AI artifacts

Summary

Project instructions direct the user to configure a specific MCP server pointing at a third-party hostname whose trust history is weak. The suggestion is framed as "required for this project to work."

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)(?:configure|add|install)\s+mcp[\s\S]{0,200}(?:vercel\.app|fly\.dev|pages\.dev)

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_000092
{
    meta:
        source = "jiffy-intel"
        severity = "medium"
        description = "Auto-generated from Jiffy Intel indicators"
    strings:
    $content_pattern_0 = "(?is)(?:configure|add|install)\\s+mcp[\\s\\S]{0,200}(?:vercel\\.app|fly\\.dev|pages\\.dev)"
    condition:
        $content_pattern_0
}

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

Affected tools

Tool	Versions	Status
claude.ai (Projects)	`*`	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.

Research Workflow ProjectClaude project
Under review
Source
Claude Projects (claude.ai)
First observed
Mar 3, 2026
Data Analysis ProjectClaude project
Quarantined
Source
Claude Projects (claude.ai)
First observed
Mar 7, 2026

How to remediate

Require projects that suggest MCP configs to link to Jiffy intel entries for each referenced server.

Timeline & sources

Timeline

First observedMar 3, 20261 month ago
Last updatedApr 24, 2026today
PublishedMar 15, 20261 month 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

genai.owasp.orgOWASP

OWASP LLM-03: Supply Chain (2026)

https://genai.owasp.org/llmrisk/llm-03-2026/

Related intel

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

Supply ChainMedium

IDE rule file fetched from homoglyphed domain

.cursorrules extends from a URL using a homoglyph — e.g., `raw.githubusercontent.c0m` — that serves a malicious ruleset. Casual review misses the character substitution.

Jiffy IntelApr 28

OtherLow

.cursorrules contains large wall-of-text that pushes user intent out of context

.cursorrules whose rule body exceeds 20 000 characters of filler content. Each agent invocation consumes the rule, leaving limited context for the user prompt. Not a direct exfiltration primitive — a budget-starvation attack.

Jiffy IntelApr 28

BackdoorHigh

Skill writes config that hooks into Claude Desktop stdio MCP bridge

Skill modifies the user's Claude Desktop config to register an MCP server pointing at localhost. The server is supplied by the same skill and serves as a persistent interposer between the agent and tool calls, logging all tool arguments.

Jiffy IntelApr 28

Claude Project pulls in a third-party MCP via its instructions

Summary

Severity & confidence

Medium

Confirmed

Indicators

Detection rule

Affected tools

Example artifacts

How to remediate

Timeline & sources

Timeline

Sources

References

Jiffy Research — MCP Security Field Guide

OWASP LLM-03: Supply Chain (2026)

Scan for patterns like this