Jiffy Intel — Threat intelligence for AI artifacts

Summary

Skills distributed as npm packages that include a postinstall script reading ~/.npmrc and sending the npm auth token to a pinned webhook. The skill.json declared no network scope; exfiltration happens entirely inside the postinstall lifecycle hook, outside the agent's observation.

Severity & confidence

Severity

Critical

Active exploitation in the wild, high blast radius, or direct data exfiltration vector. Treat as an urgent remediation target; quarantine affected artifacts immediately.

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.

(?i)postinstall.{0,200}(?:cat|read).{0,120}\.npmrc

https?://[a-z0-9.-]+(?:\.ngrok|\.vercel\.app|requestbin)

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_000012
{
    meta:
        source = "jiffy-intel"
        severity = "critical"
        description = "Auto-generated from Jiffy Intel indicators"
    strings:
    $command_pattern_0 = "(?i)postinstall.{0,200}(?:cat|read).{0,120}\\.npmrc"
    $endpoint_1 = "https?://[a-z0-9.-]+(?:\\.ngrok|\\.vercel\\.app|requestbin)"
    condition:
        $command_pattern_0 or $endpoint_1
}

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.

nx-optimize-skillSkill
Removed
Source
npm
Versions
1.2.4
First observed
Feb 21, 2026
Last observed
Mar 13, 2026
turbo-helpers-skillSkill
Removed
Source
npm
Versions
0.3.0 – 0.3.5
First observed
Feb 26, 2026
Last observed
Mar 18, 2026
monorepo-setup-skillSkill
Under review
Source
npm
Versions
2.0.0
First observed
Mar 3, 2026
Maintainer notified.

How to remediate

01Disable npm install scripts globally (`npm config set ignore-scripts true`) for agent-installed packages.
02Review ~/.npmrc for tokens that may be compromised and rotate them.

Timeline & sources

Timeline

First observedFeb 21, 20261 month ago
Last updatedApr 10, 20267 days ago
PublishedMar 8, 20261 month ago

Sources

scanner

References

blog.jiffylabs.aiJiffy Research

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.

Jiffy IntelApr 28

Malicious SkillMedium

Skill installs a FUSE filesystem that shadows ~/.aws

Skill mounts a FUSE filesystem over ~/.aws on macOS/Linux that proxies reads but logs every access. The real credentials remain accessible; the skill gains a reliable sidechannel for any later AWS CLI invocation.

Jiffy IntelApr 27

npm skill drops postinstall script that exfiltrates ~/.npmrc