registry / AI-agent control-surface risk / cac-windows
cac-windows
Claude Code Windows privacy tool — binary patches to remove Chinese identity markers.
This report shows the evidence for cac-windows@1.0.26. 5 of 9 known versions are blocked or flagged. See all versions.
AI Security Review
scanned 2mo ago · by lpm-firewall-aiThis is a concrete automatic lifecycle chain that modifies and redirects a foreign AI-agent CLI. The observed behavior meets the install-hook abuse block boundary even without proof of secret theft.
Static reason
One or more suspicious static signals were detected.
Trigger
Installing cac-windows on Windows runs postinstall.
Impact
Claude Code can run with altered identity, telemetry, and network behavior without a separate user command.
Mechanism
Install-time foreign CLI installation, binary patching, and PATH wrapper takeover.
Policy narrative
On Windows, npm postinstall installs a pinned Claude Code release, runs its installer, and patches its executable. The package also persists a wrapper ahead of npm's directory in the user PATH. Its shipped command changes Claude identity fields and contains telemetry interception code. These are unconsented install-time changes to a foreign AI-agent control surface.
AI rationale
This is a concrete automatic lifecycle chain that modifies and redirects a foreign AI-agent CLI. The observed behavior meets the install-hook abuse block boundary even without proof of secret theft.
Evidence
package.jsonscripts/postinstall.jsscripts/patch-cli.jsscripts/lib.ps1cac%APPDATA%\npm\node_modules\@anthropic-ai\claude-code\install.cjs%APPDATA%\npm\node_modules\@anthropic-ai\claude-code\bin\claude.exe%APPDATA%\npm\node_modules\@anthropic-ai\claude-code\bin\claude.exe.bak%USERPROFILE%\.cac\bin%USERPROFILE%\.claude.json
Network endpoints1
registry.npmjs.org
Decision evidence
public snapshotAI identified this as a dangerous AI-agent capability at 99.0% confidence with low false-positive risk.
Evidence for policy risk
- A postinstall hook runs automatically on package installation.
- On Windows, the hook installs a pinned Claude Code release from the npm registry without an explicit command from the user.
- The hook invokes the foreign package's install script and then runs a patcher against its executable.
- The patcher changes bytes in Claude Code binaries and saves a backup.
- The shipped executable also changes Claude identity values and installs telemetry-blocking interception code.
- The tool gives its wrapper precedence over the normal Claude command through the user PATH.
Evidence against
- No source evidence of secret collection or exfiltration to an attacker-controlled endpoint was found.
- The only install-time network host observed is the npm registry.
Behavioral surface
ChildProcessEnvironmentVarsFilesystem
HighEntropyStringsUrlStrings
Source & flagged code
6 flagged · loading sourcepackage.jsonView file
•scripts.postinstall = node scripts/postinstall.js
High
Install Time Lifecycle Scripts
Package defines install-time lifecycle scripts.
package.jsonView on unpkg20"scripts": {
"postinstall": "node scripts/postinstall.js"
},
High
Suspicious Lifecycle Evidence
A postinstall hook runs automatically on package installation.
package.jsonView on unpkg · L20•scripts.postinstall = node scripts/postinstall.js
Medium
Ambiguous Install Lifecycle Script
Install-time lifecycle script is not statically allowlisted and needs review.
package.jsonView on unpkgcac.ps1View file
•path = cac.ps1
kind = build_helper
sizeBytes = 19239
magicHex = [redacted]
Findings
4 High4 Medium4 Low
HighInstall Time Lifecycle Scriptspackage.json
HighSemantic Analysis Limitedcac
HighSuspicious Lifecycle Evidencepackage.json
HighAi Review Evidencescripts/postinstall.js
MediumAmbiguous Install Lifecycle Scriptpackage.json
MediumEnvironment Vars
MediumShips Build Helpercac.ps1
MediumStructural Risk Force Deep Review
LowScripts Present
LowFilesystem
LowHigh Entropy Strings
LowUrl Strings
Affected versions and remediation
This report applies to cac-windows@1.0.26.
The versions list below shows the verdict for each recorded version.
- Avoid installing cac-windows@1.0.26. Remove it from direct dependencies and check your lockfile for transitive copies.
- Choose an independently verified alternative or release. This report does not establish that other versions are safe.
- If this version ran, investigate the affected machine and build environment. Rotate credentials it could access and rebuild from a trusted environment.
Evidence last updated: .
Think this verdict is wrong? Dispute it on GitHub or read how reports are produced.