Unix For Rubyists
summary
A Ruby bank script creates 51 FIFO files and forks 51 child processes to represent pins; the combination is five numbers and the process prints it on SIGUSR1 but that output goes to a different TTY. The exploit uses strace -p to see write syscalls reveal the combo, lsof to find the FIFO path, echo to poke pins, and gdb to close and reopen file descriptor 1 onto /dev/pts/X so the combo prints locally. An alternate vector demonstrates ssh agent forwarding risks by exporting SSH_AUTH_SOCK to hijack keys and reach the vault.
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chapters (11)
- 0:00Introduction and setup
- 5:20What is UNIX
- 11:32UNIX concepts for Rubyists
- 17:56Step one get the combination
- 20:06Step two enter the combination
- 23:18Recovering lost terminal output
- 23:38Process forking in UNIX
- 28:42Fork exec pattern
- 31:40SSH agent hijacking
- 35:36Summary and security tips
- 36:20Contest winners and Q&A
