_blackb3ard/pwn

Arab Sec Cyber Wargames: check

category: Reverse Engineering

tl;dr: control environment variables to print out flag

[hacker’s log]: It’s almost been a year after I played a CTF due to the fact that the old laptop I was using broke. Now that I was given a new one, I wanted to play CTFs immediately but forgot how to solve challs. For real this time, I want to polish my skills in RE and PWN.

Analysis

Running the file utility on the binary displays the following results, then running it for the first time shows something about checking the machine:

$ file check
check: ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.2, BuildID[sha1]=59113482c142bbe39071d77bf2a2a1bc0c4fe948, for GNU/Linux 3.2.0, stripped

$ ./check
[-] Checking machine...
[×] Machine not OK.

We have a stripped binary which is a pain in the ass to reverse. Loaded up the binary in IDA (first time ill be using it) and thoroughly reversed each part of the program.

_blackb3ard/pwn_exhibit$

pwn notes from an exploit dev wannabe

Arab Sec Cyber Wargames: check

category: Reverse Engineering

tl;dr: control environment variables to print out flag

[hacker’s log]: It’s almost been a year after I played a CTF due to the fact that the old laptop I was using broke. Now that I was given a new one, I wanted to play CTFs immediately but forgot how to solve challs. For real this time, I want to polish my skills in RE and PWN.

Analysis

Running the file utility on the binary displays the following results, then running it for the first time shows something about checking the machine:

We have a stripped binary which is a pain in the ass to reverse. Loaded up the binary in IDA (first time ill be using it) and thoroughly reversed each part of the program.