Full Disclosure mailing list archives

Re: Month of ActiveX Bug


From: "Steven Adair" <steven () securityzone org>
Date: Tue, 1 May 2007 12:49:49 -0500 (EST)

I think a good share of the time when someone states that the DoS may
"possibly" lead to remote code execution are making such a statement for a
couple different reasons:

1) They found a DoS and truly have no idea whether or not it can cause
remote code execution due to not having the knowledge/skills necessary to
check for it and/or lack of time to make such a determination.

2) They have seen characteristics that would indicate that remote code
execution is possible but have not quite been able to nail down a working
exploit "should" one be possible.

I do not think the evidence quickly available to us would bring us to
conclude most DoS's end up resulting in remote code execution -- or even
have the ability to.  I would agree saying "often enough" would be better
than "most."

However, regardless of whether it results in remote code execution, I
don't think a DoS should necessarily be discounted as frivolous or
irrelevant.  It might not rank up there with critical or high
vulnerabilities, but it is a vulnerability nonetheless.

Steven
securityzone.org

Ok 'most' is probably bad wording on my part how does 'often enough' sound
:).

"Buffer overflow in the png_decompress_chunk function in pngrutil.c in
libpng before 1.2.12 allows context-dependent attackers to cause a
denial of service and possibly execute arbitrary code"
http://www.securityspace.com/smysecure/catid.html?id=57643

"Buffer overflow in efingerd 1.5 and earlier, and possibly up to 1.61,
allows remote attackers to cause a denial of service and possibly
execute arbitrary code via a finger request from an IP address with a
long hostname that is obtained via a reverse DNS lookup."
http://cve.mitre.org/board/archives/2003-03/msg00013.html

"A BrightStor ARCserve Backup contains four
vulnerabilities that can allow a remote attacker to cause a denial
of service or possibly execute arbitrary code."
http://packetstorm.linuxsecurity.com/0703-advisories/CAID-McAfee.txt


Note the use of 'possibly'. If it was possible then 'possibly' wouldn't be
used.

I'm not going to debate the validity of the month of activex bugs because
frankly I don't care, merely
that a DOS can turn out to be more and that at times either the researcher
hasn't spent enough time on it, can't get the POC working, or lacks the
skill to fully understand the problem.

There have been multiple instances on the securityfocus lists throughout
the years where a DOS suddenly
became promoted to a remotely exploitable bug (i.e another person found it
was actually exploitable). I'm not going
to find them and post them here, but a little googling can yield
results.

- Robert
http://www.cgisecurity.com/

Consider that most often a bug filed as DOS can actually be
exploitable, but the person who discovered it can't get the POC working
or is even aware it is. While command execution is the ideal goal it
doesn't mean other types of issues are *completely* worthless.  =20

Most often? How do you know that?

Larry Seltzer
eWEEK.com Security Center Editor
http://security.eweek.com/
http://blogs.eweek.com/cheap_hack/
Contributing Editor, PC Magazine
larryseltzer () ziffdavis com=20


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