A minimal example to shellcode in rust, this is an example of my post <zom.wtf/posts/shellcoding-in-rust>.
const N: u64 = 100;
// our shellcode
#[no_mangle]
pub fn _start() {
let mut buffer = [0; 1024];
let mut sum = 0;
for i in 0..N {
let start = rdtsc();
buffer[i as usize] = 0;
let end = rdtsc();
sum += end - start;
}
print!(sum / N);
}Compile the shellcode with:
RUSTFLAGS="-C relocation-model=pie" cargo build --release --target="x86_64-unknown-none"View the shellcode with:
objdump -D ./target/x86_64-unknown-none/release/shellcode -M intel -j .text
./target/x86_64-unknown-none/release/shellcode: file format elf64-x86-64
Disassembly of section .text:
000000000000120d <.text>:
120d: 6a 64 push 0x64
120f: 5f pop rdi
1210: 31 c9 xor ecx,ecx
1212: 48 83 ef 01 sub rdi,0x1
1216: 72 1d jb 0x1235
1218: 0f 31 rdtsc
121a: 48 89 d6 mov rsi,rdx
121d: 48 c1 e6 20 shl rsi,0x20
1221: 48 09 c6 or rsi,rax
1224: 0f 31 rdtsc
1226: 48 c1 e2 20 shl rdx,0x20
122a: 48 09 c2 or rdx,rax
122d: 48 29 f1 sub rcx,rsi
1230: 48 01 d1 add rcx,rdx
1233: eb dd jmp 0x1212
1235: 50 push rax
1236: 6a 64 push 0x64
1238: 5e pop rsi
1239: 48 89 c8 mov rax,rcx
123c: 31 d2 xor edx,edx
123e: 48 f7 f6 div rsi
1241: 48 89 c1 mov rcx,rax
1244: 51 push rcx
1245: 48 c7 c2 08 00 00 00 mov rdx,0x8
124c: 48 89 e6 mov rsi,rsp
124f: 48 c7 c7 01 00 00 00 mov rdi,0x1
1256: 48 c7 c0 01 00 00 00 mov rax,0x1
125d: 0f 05 syscall
125f: 58 pop rax
1260: c3 ret