reverseProeasy

Heap Allocator

ringzer0ctf

Task: not-stripped ELF64 'Heap Allocator' shows only malloc/free noise and a 'No Flag then' decoy. Solution: the flag is built in an .init_array constructor gated by a cmp against 0xcc (INT3); setting a GDB breakpoint at the compared byte flips the gate and the banner leaks the flag.

elf reverse anti_reverse not_stripped constructor init_array gdb debugger breakpoint int3

init_array_constructor_analysisint3_breakpoint_gatestatic_patch_je_to_jmpbanner_overwriteencrypted_writeup_flag_oracle

$ ls tags/ techniques/

elf reverse anti_reverse not_stripped constructor init_array gdb debugger breakpoint int3

init_array_constructor_analysisint3_breakpoint_gatestatic_patch_je_to_jmpbanner_overwriteencrypted_writeup_flag_oracle

Analysis

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

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

Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Permission denied (requires tier.pro)

Sign in to access full writeups

$sign in

$ cat writeup.md…

Sign in to access full writeups

Sign in to access full writeups

Similar writeups