miscProhard

nodejailjailjail

Hack.lu CTF 2026

Task: A Node 26 payload must survive a char whitelist banning () [] backtick, deleted builtins, and `node --permission`; the flag is root-only behind a setuid /readflag. Solution: drive a native ROP chain from bracket-free JS via undici gadget capture and a forged FileHandle on libuv's signal-pipe fd.

nodejs sandbox_escape rop javascript_jail permission_model libuv undici structuredclone filehandle

char_whitelist_escapetoprimitive_call_primitiveundici_gadget_captureobject_defineproperty_hookstructuredclone_deserializer_abuselibuv_signal_pipe_ropfd_write_permission_bypass

$ ls tags/ techniques/

nodejs sandbox_escape rop javascript_jail permission_model libuv undici structuredclone filehandle

char_whitelist_escapetoprimitive_call_primitiveundici_gadget_captureobject_defineproperty_hookstructuredclone_deserializer_abuselibuv_signal_pipe_ropfd_write_permission_bypass

Analysis

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$ python3 exploit.py --target 192.168.1.1 --port 8080
[*] Connecting to target...
[+] Shell obtained!

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