Offensive Lab · pro · solved in-browser (no VM needed) · 3 tiered hints
Your own disposable practice box. The sudoers file keeps LD_PRELOAD in the environment (env_keep += "LD_PRELOAD") for a NOPASSWD rule that lets you run /usr/bin/somebin as root. You have compiled a malicious shared object at /home/player/evil.so whose constructor spawns a root shell. Write /home/player/ans.txt with the single command that runs the allowed binary under sudo while setting LD_PRELOAD to /home/player/evil.so so your library loads inside the root process. (Authored config, graded structurally — the engine isn't run here.)
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Authorized local-privilege-escalation wargames on a disposable box you own.
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Is it free? Yes — play as a guest, no signup required to start.
Do I need to install anything? No. Everything runs in your browser.
How is it graded? Automatically and deterministically — your work is checked against the exact rules the live box would apply.