Chain Reaction

A control system for initiating chain reactions has a familiar input flaw. But the security has been upgraded, and old tricks won't work on this 64-bit system.

Your mission: find a new way to trigger the hidden sequence.

Binary Information:

Filename: chain-reaction
Size:     13,384 bytes (13 KB)
MD5:      c9b800d520155bb9771596e212d8b0a2
SHA1:     7e8233d792fd54ee91ea08abae293e32b84e1eea
SHA256:   ac341cceb198035465a69fefc0d2a09e850ddffbf7791ee6303d9cfa6966e1b4

Verify integrity after download:

md5sum chain-reaction && sha1sum chain-reaction && sha256sum chain-reaction

Environment:
- Architecture: x86_64 (64-bit)
- Stack protector: Disabled
- NX: Enabled
- PIE: Disabled
- RELRO: None
- Symbols: Not stripped

Tip: The hidden function will not run unless it receives a specific argument...

Note: Download the binary for local analysis. It reads flag.txt from the current directory - use a dummy flag for testing. The real flag can only be captured by exploiting the live instance on the lab.