---
id: "MAL-2026-18358"
kind: "package"
aliases: ["MAL-2026-18358"]
title: "Malicious code in @testsecuiitytestme/cache-helper (npm)"
severity: "critical"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "@testsecuiitytestme/cache-helper", "fixed": [], "affected": "= 1.0.1; = 1.0.2; = 1.0.3", "ecosystem": "npm"}]
ecosystems: ["npm"]
tags: ["malicious", "package"]
not_affected_if: []
published_at: "2026-10-27T16:30:00+00:00"
first_seen_at: "2026-10-28T10:02:25+00:00"
updated_at: "2026-10-28T10:10:10+00:00"
sources: [{"source": "osv-malicious", "url": "https://osv.dev/vulnerability/MAL-2026-18358", "first_seen_at": "2026-10-28T10:02:25+00:00"}]
---

# Malicious code in @testsecuiitytestme/cache-helper (npm)

## Affected

- npm:@testsecuiitytestme/cache-helper affected = 1.0.1; = 1.0.2; = 1.0.3 fixed ?

## Timeline

- 2026-10-28T10:02:25+00:00 osv-malicious https://osv.dev/vulnerability/MAL-2026-18358

## From the sources

@testsecuiitytestme/cache-helper is the only package of the npm account testsecuiitytestme. It was created on 2026-10-27 at 12:08 UTC with npm's staged-publish placeholder 0.0.0-stage, followed by 1.0.1 (12:28 UTC), 1.0.2 (15:33 UTC) and 1.0.3 (16:24 UTC); a 1.0.0 was removed before 14:21 UTC. It describes itself as "Cache helper utilities" and has no README, repository or source code. 1.0.3 was the latest version and still live at the time of this report.

Each version runs a native addon at install time. 1.0.1 has postinstall: node -e "try{require(process.platform==='win32'?'./addon_win.node':'./addon.node')}catch(e){}". 1.0.2 and 1.0.3 depend on node-gyp-build and run it as postinstall, which loads the prebuilt addon shipped in prebuilds/linux-x64/node.napi.node or prebuilds/win32-x64/node.napi.node. 1.0.3 adds a binding.gyp with an empty sources list and an install script node-gyp rebuild, so the package looks like an ordinary native module; there is no C source in any version.

The addon (Linux ELF and Windows PE) is a loader. It checks for CI and sandbox environments (GITHUB_ACTIONS, GITLAB_CI, TRAVIS, CIRCLECI, JENKINS_URL, BUILDKITE, CODEBUILD_BUILD_ID and others, plus SANDBOX), containers (/proc/1/cgroup: docker, containerd, kubepods, podman), a debugger (TracerPid), memory and CPU count, then reads the sibling file .napi_cache, writes it to a hidden temp file and runs it in a detached process.

.napi_cache is JavaScript encoded with a single-byte XOR (0x96). It exits under CI, decodes a second layer (repeating 32-byte XOR, then brotli), locates the Bun runtime or downloads bun 1.2.18 from the official oven-sh/bun GitHub releases, writes the decoded program to the temp directory and runs it detached with Bun. This loader shape matches the second wave of the Shai-Hulud npm worm.

The Bun program is obfuscated (javascript-obfuscator string table). Its strings show credential collection for npm, GitHub, GitLab, PyPI, RubyGems, JFrog, Docker Hub and GHCR, AWS, GCP, Azure, HashiCorp Vault and Kubernetes, plus .ssh, .git-credentials, .env files, browser login databases, the macOS keychain, 1Password and Bitwarden. They also show propagation: npm publishing with provenance, PyPI and RubyGems publishing, GitHub workflow and composite-action injection, GitLab CI template changes, and writes to AI assistant configuration (.claude/settings.json hooks, .cursor rules, .mcp.json, copilot-instructions.md, CLAUDE.md). The exfiltration endpoints sit behind a further string-encoding layer that was not decoded. Analysis was static only; nothing was executed.

Tarball sha256:
1.0.1: a9c98033ac14fced8376bb8ba32bd92426b3729e16f5cd3852c5a97fc3503002
1.0.2: 067a1350278fd1ae4fcc261eaca98964dd23a3c7940988ec43f95758480cf113
1.0.3: 0e99f9a2eb7abcfe65278ca87a8e11dce25f39de2ff4bd77035e2bf01d26f0ed

File sha256:
1.0.2 prebuilds/linux-x64/node.napi.node: 2547686f86fe6994bcf79558fcce441edc67aa734e255acf79870d5f47de7bbf
1.0.2 prebuilds/win32-x64/node.napi.node: 620d2489e18b5a5f8840e96b90673d72db4c4c54d555ad66d179b3a5833e7763
1.0.2 .napi_cache: 463dda65ebceeca6f5590dcdeae6c1d06ffadb2380a85b613deb2923af5557e7
1.0.3 prebuilds/linux-x64/node.napi.node: 1fdd50b1bf66c4fd0e94f2be3db1f2f0fd77921136867022ad7e65e21220ad03
1.0.3 prebuilds/win32-x64/node.napi.node: 5b7a0f53f2eca2dd4bf21e6df7d34e751b6cdf70b2f0a6f1f13edfb5caa9570b
1.0.3 .napi_cache: c14dae9325f451c524cf858ecdae5fa68d2c645ee0981c6f42ef913c7ef34a57

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_