How a sandwich defeats North Korea's hackers (and the US couldn't for 70 years)

Brenn Hill — Thu, 02 Apr 2026 06:11:21 +0000

Two days ago, Google's Mandiant team attributed the axios npm compromise to UNC1069 — a North Korean threat group previously linked to cryptocurrency theft and attacks on DeFi platforms. The malicious code shares significant overlap with WAVESHAPER, a C++ backdoor Mandiant attributed to the same group in February.

North Korea just weaponized the most popular HTTP client in JavaScript. 100 million weekly downloads. The payload: a cross-platform RAT that harvests credentials, SSH keys, and cloud tokens from every developer machine that runs npm install.

The United States has spent 70 years and trillions of dollars trying to contain North Korea. Nuclear negotiations, sanctions, carrier groups, diplomatic pressure, UN resolutions. None of it has stopped the DPRK from becoming one of the most effective cyber threats on the planet.

A sloppy joe sandwich stops them in 3 seconds.

What happened

On March 30, the attacker compromised the npm account of axios's lead maintainer (jasonsaayman) using a stolen access token. They changed the account email to a Proton Mail address and published two malicious versions:

axios@1.14.1 — published March 31, 00:21 UTC
axios@0.30.4 — published March 31, 01:00 UTC

Both versions injected a new dependency: plain-crypto-js@4.2.1. This package was never imported anywhere in the axios source. Its sole purpose was to run a postinstall hook that deployed platform-specific RATs:

macOS: Binary at /Library/Caches/com.apple.act.mond, executed via AppleScript
Windows: PowerShell RAT with Registry persistence and in-memory binary injection
Linux: Python RAT script via nohup

The dropper script deleted itself after execution to hide forensic evidence. The attacker staged plain-crypto-js 18 hours in advance, pre-built three platform payloads, and hit both release branches within 39 minutes. This was not amateur hour.

How sloppy-joe blocks every layer of this attack

sloppy-joe is an open-source supply chain security tool. It runs before npm install. It reads your package-lock.json and checks every dependency — direct and transitive — against multiple independent signals. No packages are downloaded. No code is executed.

Signal 1: Version age gate

ERROR axios [metadata/version-age]
      Version '1.14.1' of 'axios' was published 0 hours ago (minimum: 72 hours).
      New versions need time for the community and security scanners to review them.
 Fix: Wait until the version is at least 72 hours old, or pin to an older version.

The compromised versions were live for 2-3 hours before npm yanked them. A 72-hour gate means they never get installed. Period. This requires zero knowledge of the attack — it works purely on the principle that new versions should survive community review before hitting production.

This single check stops the attack.

But sloppy-joe doesn't stop at one signal. With --deep transitive scanning, plain-crypto-js gets demolished by five independent checks:

Signal 2: New package detection

ERROR plain-crypto-js [metadata/new-package]
      'plain-crypto-js' was first published 0 days ago. New packages are higher
      risk — verify this is a legitimate, maintained project before depending on it.
 Fix: Verify 'plain-crypto-js' at its registry page and source repository.

plain-crypto-js was created the day before the attack. Brand new packages as transitive dependencies of 100M-download packages are inherently suspicious.

Signal 3: Install script risk amplifier

ERROR plain-crypto-js [metadata/install-script-risk]
      'plain-crypto-js' has install scripts AND was published 0 days ago and with
      0 downloads. Install scripts on new, low-download packages are the #1
      malware delivery vector.
 Fix: Do not install this package. Verify it is legitimate before proceeding.

Install scripts + new package + zero downloads. This is the exact fingerprint of a supply chain attack. sloppy-joe's install script risk signal combines multiple weak signals into a high-confidence detection. Every real-world npm supply chain attack in the last 5 years has matched this pattern.

Signal 4: No source repository

WARNING plain-crypto-js [metadata/no-repository]
        'plain-crypto-js' has no source repository URL and is a new package
        (< 30 days old). Legitimate packages almost always link to their source code.
 Fix: Verify 'plain-crypto-js' at its registry page.

Legitimate packages link to their GitHub/GitLab repo. Malicious packages created as payload delivery vehicles don't bother.

Signal 5: Name similarity

WARNING plain-crypto-js [similarity/mutation-match]
        'plain-crypto-js' is suspiciously similar to existing package 'crypto-js'
 Fix: Verify this is the package you intend to use.

plain-crypto-js is a clear attempt to look like crypto-js — a real, popular cryptography package with hundreds of millions of downloads. sloppy-joe's mutation generators catch this.

Five signals. One sandwich. Zero dollars.

Here's what's remarkable: none of these detections require threat intelligence feeds, malware signature databases, or AI-powered behavioral analysis. They're all variations of the same primitive: cross-reference what the code claims to use against what actually exists on the registry.

Is the version too new? Flag it.
Is the transitive dep brand new? Flag it.
Does a brand new package have install scripts? Block it.
Does it have no source repository? Flag it.
Does the name look like a popular package? Flag it.

Each signal alone is informational. All five firing together on the same package is a certainty.

The cost of this defense

# Add to any CI pipeline
npx sloppy-joe check

That's it. One line. Runs in 5-15 seconds. No account needed. No API key. No subscription. Open source, MIT licensed.

The DPRK's UNC1069 spent 18 hours staging payloads, pre-building RATs for three platforms, and compromising a maintainer account. sloppy-joe catches it in the time it takes to read a package-lock.json.

What sloppy-joe can't catch

Honesty matters: sloppy-joe would not have detected the credential theft itself. The attacker hijacked the real maintainer's account — the npm _npmUser field still shows jasonsaayman. There's no publisher change to detect. npm's provenance attestation (OIDC-based publishing via GitHub Actions) is the real defense against token theft — the malicious versions were published manually, bypassing axios's CI pipeline.

sloppy-joe catches the payload, not the compromise. But the payload is what hurts you.

Get started

# Install
cargo install sloppy-joe

# Run
sloppy-joe check

# In CI (GitHub Actions)
- uses: brennhill/sloppy-joe-action@v1

brennhill / sloppy-joe

Shields against supply-chain, slopsquatting, and typosquatting attacks from dependencies and code.

Catch hallucinated, typosquatted, and non-canonical dependencies
before they reach production.

cargo install sloppy-joe

The LiteLLM supply chain attack (March 2026) compromised a package with 97M monthly downloads. Attackers stole publishing credentials, pushed malicious versions that harvested SSH keys, cloud credentials, and K8s secrets. sloppy-joe's default 72-hour version age gate would have blocked both poisoned versions — they were discovered within hours, well before the gate would have opened. If you run sloppy-joe check in CI, this attack fails. Full analysis

AI code generators hallucinate package names ~20% of the time. Attackers register those names and wait. sloppy-joe catches them in CI before npm install or pip install runs.

How to Use

# Install (single static binary, no runtime dependencies)
cargo install sloppy-joe
# Or download an auditable binary archive from GitHub Releases
# https://github.com/brennhill/sloppy-joe/releases

# Check current project — auto-detects ecosystem from manifest files
sloppy-joe check

# Check a

…

View on GitHub

sloppy-joe is an open-source supply chain security tool that catches hallucinated, typosquatted, and compromised dependencies before they reach production. It runs before your package manager, requires no code execution, and blocks attacks like axios, LiteLLM, event-stream, and ua-parser-js.

DEV Community: Brenn Hill