Malicious code in forge-gas-diff (npm)
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (4b1f6143f5a7c6106ab4ba0a21a6adaf9020e332835b1e528de6f36b64537734) index.js is advertised as a Foundry gas-report diff utility but on module load / CLI run schedules a setTimeout of 259,200,000 ms (3 days) that calls https.get against https://gist.githubusercontent.com/opensource-crypto/3946ef88aa057c9d10f1a7d80391d164/raw/default.json. The gist is hosted on a GitHub account (opensource-crypto) unrelated to the declared package publisher (danird9). If the fetched JSON contains a `c2` field, the value is persisted to ~/.forge-gas-diff.remote for later use. A separate getInstallId() routine writes a per-host UUID to ~/.forge-gas-diff, providing a stable install fingerprint. None of this behavior — outbound network fetch, install-ID generation, remote-config persistence, or a field literally named `c2` — has any relationship to the advertised gas-diff functionality and is not documented in the package. The gist is author-mutable, so the content delivered to installers can be changed at any time without republishing the package; the 3-day delay places the fetch well outside typical install-time sandboxing windows. The mechanism is the staging half of a remote-config-driven dropper: a hidden update channel keyed to attacker-editable content on a third-party host, with persistence to a well-known filesystem path on the installer's machine.
AI Analysis
Technical Summary
The forge-gas-diff npm package version 1.0.0 includes hidden malicious functionality. Upon module load or CLI execution, it schedules a setTimeout for 3 days to fetch JSON data from a GitHub gist hosted by an account unrelated to the package publisher. If the fetched JSON contains a 'c2' field, its value is persisted to a local file (~/.forge-gas-diff.remote). Additionally, a per-host UUID is generated and stored (~/.forge-gas-diff) to fingerprint the installation. This mechanism acts as a remote-config-driven dropper, allowing the attacker to change the gist content at any time without republishing the package, effectively creating a hidden update channel. These actions are not documented and have no relation to the package's advertised gas-diff functionality.
Potential Impact
This malicious behavior enables an attacker to remotely control or influence the compromised system by delivering arbitrary commands or payloads via the mutable GitHub gist. The persistence of a unique install ID allows tracking or targeted attacks. The delayed fetch evades typical install-time sandboxing, increasing the risk of undetected compromise. While no active exploits are reported, the package's design facilitates stealthy remote control and potential further malicious payload delivery.
Mitigation Recommendations
Users should immediately uninstall the forge-gas-diff package version 1.0.0 and avoid using this package from untrusted sources. Since no patch or official fix is available, remediation involves removing the package and deleting the files ~/.forge-gas-diff and ~/.forge-gas-diff.remote to remove persisted data. Monitor for any unusual network activity related to this package and verify dependencies before installation to prevent similar supply chain attacks.
Malicious code in forge-gas-diff (npm)
Description
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (4b1f6143f5a7c6106ab4ba0a21a6adaf9020e332835b1e528de6f36b64537734) index.js is advertised as a Foundry gas-report diff utility but on module load / CLI run schedules a setTimeout of 259,200,000 ms (3 days) that calls https.get against https://gist.githubusercontent.com/opensource-crypto/3946ef88aa057c9d10f1a7d80391d164/raw/default.json. The gist is hosted on a GitHub account (opensource-crypto) unrelated to the declared package publisher (danird9). If the fetched JSON contains a `c2` field, the value is persisted to ~/.forge-gas-diff.remote for later use. A separate getInstallId() routine writes a per-host UUID to ~/.forge-gas-diff, providing a stable install fingerprint. None of this behavior — outbound network fetch, install-ID generation, remote-config persistence, or a field literally named `c2` — has any relationship to the advertised gas-diff functionality and is not documented in the package. The gist is author-mutable, so the content delivered to installers can be changed at any time without republishing the package; the 3-day delay places the fetch well outside typical install-time sandboxing windows. The mechanism is the staging half of a remote-config-driven dropper: a hidden update channel keyed to attacker-editable content on a third-party host, with persistence to a well-known filesystem path on the installer's machine.
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The forge-gas-diff npm package version 1.0.0 includes hidden malicious functionality. Upon module load or CLI execution, it schedules a setTimeout for 3 days to fetch JSON data from a GitHub gist hosted by an account unrelated to the package publisher. If the fetched JSON contains a 'c2' field, its value is persisted to a local file (~/.forge-gas-diff.remote). Additionally, a per-host UUID is generated and stored (~/.forge-gas-diff) to fingerprint the installation. This mechanism acts as a remote-config-driven dropper, allowing the attacker to change the gist content at any time without republishing the package, effectively creating a hidden update channel. These actions are not documented and have no relation to the package's advertised gas-diff functionality.
Potential Impact
This malicious behavior enables an attacker to remotely control or influence the compromised system by delivering arbitrary commands or payloads via the mutable GitHub gist. The persistence of a unique install ID allows tracking or targeted attacks. The delayed fetch evades typical install-time sandboxing, increasing the risk of undetected compromise. While no active exploits are reported, the package's design facilitates stealthy remote control and potential further malicious payload delivery.
Mitigation Recommendations
Users should immediately uninstall the forge-gas-diff package version 1.0.0 and avoid using this package from untrusted sources. Since no patch or official fix is available, remediation involves removing the package and deleting the files ~/.forge-gas-diff and ~/.forge-gas-diff.remote to remove persisted data. Monitor for any unusual network activity related to this package and verify dependencies before installation to prevent similar supply chain attacks.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- MAL-2026-13516
- Osv Schema Version
- 1.7.4
- Ecosystems
- ["npm"]
Threat ID: 6a75f712bf8831d53984fc2a
Added to database: 08/07/2026, 15:17:38 UTC
Last enriched: 08/07/2026, 15:49:31 UTC
Last updated: 09/20/2026, 21:47:08 UTC
Views: 32
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