Serial (150 pts)¶
Run and capture the flag!
Analyze the file by Trid.
$ ./trid_Linux64 serial TrID/64 - File Identifier v2.20 - (C) 2003-15 By M.Pontello Definitions found: 5988 Analyzing... Collecting data from file: serial 49.7% (.) ELF Executable and Linkable format (Linux) (4025/14) 49.4% (.O) ELF Executable and Linkable format (generic) (4000/1) 0.7% (.CEL) Lumena CEL bitmap (63/63)
So this is an ELF file. Analyze the file by IDAPro! Unfortunately, you can not get usefull information by reversed code! It seems the app used
anti-disassembling techniques! So, lets debugging it.
gdb for debugging the app. In this question you should use debugger instead of disassembler. After giving input, set a breakpoint and follow the instructions, there are many simple comparing instruction. The flag is