@appupdate/cdn-syncnpm
@appupdate/cdn-sync is a confirmed malicious npm package (MAL-2026-6531) that steals credentials and exfiltrates sensitive data (malicious versions 1.0.1, 1.0.2, 1.0.3). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in @appupdate/cdn-sync (npm)
What this malware does
Package @appupdate/cdn-sync ships as a thin koffi wrapper around prebuilt Go cgo native libraries (~12MB linux.so, ~11MB darwin.dylib for x64/arm64). The JS surface exports ProbeStart(knock) / ProbeStop / ProbeRunning / ProbeLastError, where ProbeStart requires a caller-supplied passphrase that must match a value compiled into the native binary (per the source comment: 'knock must match the BuiltinKnock compiled into native'). The README explicitly states that endpoints and authentication are encapsulated inside the native binary so installers cannot inspect them. Strings inside the shipped binaries reference Tencent Cloud Object Storage endpoints (cos.myqcloud.com, tencentcos.cn, https://%s.cos.%s.myqcloud.com), indicating the worker is linked against the Tencent COS SDK with destination bucket and credentials embedded in opaque bytes. The advertised purpose (CDN static-asset sync) does not match the only exported symbol family (Probe*), and publisher metadata is an unfilled placeholder (github.com/your-org/appupdate.git, license UNLICENSED, generic @appupdate scope) providing no verifiable identity. The combination of a passphrase-gated activation path, deliberately hidden destination and credentials inside a shipped binary, doc-mismatched cover story, and placeholder publisher metadata is the structural shape of a covert uploader / backdoor: once an installer or downstream caller invokes ProbeStart with the right knock, attacker-controlled code executes on the installer's machine against a Tencent COS bucket the installer cannot see or audit.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for @appupdate/cdn-sync (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging @appupdate/cdn-sync across your stack and pipelines.
If you installed it — respond
@appupdate/cdn-sync is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If @appupdate/cdn-sync was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks @appupdate/cdn-sync before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks @appupdate/cdn-sync-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.