PicoCTF Challenge: ARMseembly4

August 11, 2025 PicoCTF Hard

Challenge Overview:

The following was the description for the challenge:

Deep dive

Since this is ARM assembly, we cannot analyze it directly with standard gdb (which is for x86/x64).
Hence, we have to install an ARM emulator(QEMU) and GCC which is a compiler.
```
sudo apt install qemu-user gcc-aarch64-linux-gnu
```
Now, we have to compile this assembly to ARM.
```
aarch64-linux-gnu-gcc -static chall_4.S -o chall_4
```
- -static: so that all libraries are bundled.
- .S: an assembly extension.

Running the Binary

Testing the behavior of the program.
But we are told that the program takes an argument.
Using the QEMU emulator:
```
qemu-aarch64 ./chall_4 3459413018
```

Printing the flag according to the format

ARMssembly