bugtraq - Re: Buffer overflow prevention

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Thu, 14 Aug 2003 20:47:21 +0200
From: Jedi/Sector One <j@...eftpd.org>
To: Mariusz Woloszyn <emsi@...rtners.pl>
Subject: Re: Buffer overflow prevention

On Thu, Aug 14, 2003 at 07:26:47PM +0200, Mariusz Woloszyn wrote:
> What we're discussing here is an internal structures and data protecting.
> IMHO the ProPolice (http://www.research.ibm.com/trl/projects/security/ssp/),
> is the best protection in this kind, even comparing to "two stack"
> approach.

  ProPolice is not magical, though. There are plenty of cases where it is
totally inefficient. To illustrate a very common one :

#include <string.h>

struct Test {	
	char str[5];
};

int main(void)
{
	struct Test x;	
	strcpy(x.str, "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA");

	return 0;
}

  Propolice doesn't see anything wrong and eip happily goes to 0x41414141.

  Propolice also doesn't give any protection against heap overflows.

  So the best protection is probably Propolice + non exec stack + write xor
executable pages. Oh, surprise, this is just how OpenBSD works.

  This is still not a magical protection against everything. A vulnerable
application can still behave abnormally after an overflow. But this couple
makes injection + execution of arbitrary code way more tricky.

  The only way to sleep quietly is still to audit the code at the first place.

-- 
 __  /*-      Frank DENIS (Jedi/Sector One) <j@...Networks.Com>     -*\  __
 \ '/    <a href="http://www.PureFTPd.Org/"> Secure FTP Server </a>    \' /
  \/  <a href="http://www.Jedi.Claranet.Fr/"> Misc. free software </a>  \/