client-cookies-agentnpm
Advisory published Updated
client-cookies-agent is a confirmed malicious npm package (MAL-2026-10019) that opens a backdoor for remote access (malicious versions 99.9.5, 99.9.6, 99.9.7). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in client-cookies-agent (npm)
What this malware does
package.json declares postinstall=node index.js, which runs automatically on npm install. index.js collects host identifiers via os.hostname(), os.userInfo(), and process.cwd(), resolves the external IPv4 address, and POSTs them as JSON to a hardcoded Interactsh-style out-of-band collector at lpzlajzjfkpfeefuzxbv6n5nob7bpuh6e.oast.fun/receive-data over plain HTTP. The package has empty description and author fields and is published at version 99.9.5, a shape consistent with a dependency-confusion squat against a private/internal package name: installing (or accidentally resolving) this name causes a reconnaissance beacon to fire from the developer or CI machine, confirming code execution on the target and leaking host, user, cwd, and network identifiers to the attacker.
The OpenSSF Package Analysis project identified 'client-cookies-agent' @ 99.9.5 (npm) as malicious.
It is considered malicious because:
- The package communicates with a domain associated with malicious activity.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Search your lockfiles and build artifacts for client-cookies-agent (3 malicious versions).
If you installed it — respond
client-cookies-agent establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If client-cookies-agent was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
- OpenSSF: Package Analysis · finder
Detect & block this
O3 blocks client-cookies-agent-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.