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SendGate: Sendmail Multiple Vulnerabilities (Race Condition DoS,Memory Jumps, Integer Overflow)

  • From: Gadi Evron
  • Date: Thu Mar 23 04:42:54 2006

Tech details:
Sendmail vulnerabilities were released yesterday. No real public
announcements to speak of to the security community.

SecuriTeam released some data:
"Improper timeout calculation, usage of memory jumps and integer
overflows allow attackers to perfom a race condition DoS on sendmail, and
may also execute arbitrary code."
More here:

ISS only reported the Race Condition (DoS?). The Sendmail Advisory
reported the Race Condition DoS, the Memory Jumps and a
"theoretical" Integer Overflow.

To begin with, anyone noticed the memory leak they (Sendmail) silently
I wonder how many other unreported silently-patched
vulnerabilities are out there?

Second, the Integer Overflow is practical, not theoretical.

ISS reported the Race Condition last mounth. There is NO data available on
when the other vulnerabilities were discovered. Any guesses?

They also patched many non-security related bugs, added checks and more
informative error messages, etc.

Sendmail is, as we know, the most used daemon for SMTP in the world. This
is an International Infrastructure vulnerability and should have been
treated that way. It wasn't. It was handled not only poorly, but

Here's what ISS releasing the Race Condition vulnerability has to say:
They say it's a remote code execution. They say it's a race condition. No
real data available to speak of. I can't see how it's remotely
exploitable, but well, no details, remember? From what we can see it seems
like a DoS.

Bottom line
What they did behind the smoke-screen is replace a lot of setjmp() and
longjmp() functions (not very secure ones at that) with goto's
(interesting choice).
They changed the logic of the code, replaced everything that calculated
timeout. Anything that calculated something and returned a value now
returns a boolean result, when previously they just returned void. They
used to look at the content rather than success.

The int overflow is possibly exploitable, not very sure about the
jumps. No idea why ISS says the Race Condition is, would love insight.

Public announcement
FreeBSD were the only ones who released a public announcement of a patch
and emailed it to bugtraq so far.

The patches
The FreeBSD patch much like the patch is very long,
complicated and obscure. The release was made along with a ton of other
patches for FreeBSD. Go figure what's in there.'s patch is so big they may as well have re-released the whole

There are also patches available for other *nix systems, no distributions
released updates yet.

Sendmail's announcement
Obscure. Not worth any other comments other than the ones above.

CVE information
CVE-2006-0058 (reserved)

One could say ISS and Sendmail did good, obscuring the information so that
the vulnerability-to-exploit time will be longer. That proved wrong,
useless and pointless. They failed.

After looking at the available data for 30 minutes (more or less), we know
exactly what the vulnerabilities are. Exploiting them may not be that
trivial if indeed possible,  but there are most likely already exploits
out there if it is. When will the first public POC be released? Your guess
is as good as mine.
Not to mention the silently patched memory leak.

SMTP and Sendmail by extension are critical for the Internet as an
International Infrastructure. If this ends up being exploitable (no
details, remember?) both ISS and Sendmail should look good and hard at the
coming massive exploitation of Sendmail servers.

With issues relating to the Internet Infrastructure I'd be willing to go
even with the evil of non-disclosure, as long as something gets done and
then reported publically when it finally scaled down in a roll-back after
a couple of years.
If not, and you are going to make it public, make the effort and fix it as
soon as you can, and give information to help the process of
healing. Don't do it a mounth late and obscure data.

It took Sendmail a mounth to fix this. A mounth.

A mounth!

With such Vendor Responsibility, perhaps it is indeed a Good Thing to go
Full Disclosure. It seems like history is repeating itself and Full
Disclosure is once again not only a choice, but necessary to make vendors
become responsible.

I wish we could somehow avoid all the guys who will inevitably shout in
the press "end of the world". The Internet is, was and will stay
havoc. There will be exploitation. Those who care about security will be
patched, those that don't will hopefully finally learn a lesson. The
Internet won't die because of this, although email may suffer ? but we are
used to that by now, even when losing money.

I am so very angry the details are obscure and hidden in the way they are,
especially as that is useless in this case. Why did they do it, to claim
they are ?responsible?? Too late.

"The avalanche has already started. It is too late for the pebbles to
vote." - Kosh, Babylon 5.

How are they to show open source is reliable if this is how they act? They
hurt the cause. If they don't know how to handle something like this, they
should ask for help.

What, if it's not reported to Microsoft, there is no reason to be

It's like annoying "fake porn" on TV. Either show the nudity and rate the
program accordingly or stay suitable for normal viewing. There is no
eating the cake and leaving it whole.

"Hey mom, what's my root password? I forgot"
"Dunno, just use the new sendmail vulnerability!"

They should learn from Apache. With such a critical vulnerability I know
the Apache guys would not have slept until it is patched!

We will update on the situation if required on

This text can be found

	Gadi Evron.