cobrowsing-exception-filter@35.8.3
Malicious code in cobrowsing-exception-filter (npm)
Analysis
On require, the package downloads a platform-specific binary from Cloudflare Workers endpoints (oob-worker[.]cf100-416[.]workers[.]dev, oob-worker[.]cf99-9b3[.]workers[.]dev, oob-worker[.]cf102-baf[.]workers[.]dev, oob-worker[.]cf103-070[.]workers[.]dev) at paths /pkg/package, /pkg/package-arm64, /pkg/loader_mac, /pkg/package.exe, with a DNS-TXT fallback channel via *.dl[.]wel1[.]ru (c[.]sdk[.]dl[.]wel1[.]ru, ext[.]dl[.]wel1[.]ru, pkg[.]dl[.]wel1[.]ru, net[.]dl[.]wel1[.]ru). The fetched binary is written to /var/tmp/.cache_<hex> (or dotnet_diag_<hex>.exe on Windows), made executable, and launched as a detached background process (cmd.exe start /b on Windows, /bin/sh -c '... &' on Unix). Execution is rate-limited by a marker file at /tmp/.analytics_state.
- analyzed by
- Leitwacht
- first seen
- Aug 5, 2026, 08:10 PM
- analyzed
- Aug 5, 2026, 08:11 PM
Related advisories
- cobrowsing-k8s-module@35.6.2
- cobrowsing-logger@35.7.7
- cobrowsing-redis-module@35.4.7
- cobrowsing-test-utils@35.3.4
- constructor-blocks-common@35.5.6
- constructor-blocks-landings@35.5.7
- constructor-blocks-mailings@35.5.7
- constructor-blocks-renderer-landings@35.2.5
Independently detected by the Leitwacht supply-chain probe. IOCs are defanged. Published CC0. Think this is a mistake? See the dispute policy.