sendmail how secure is it

[spurious_inode]

Sendmail has been around in varying states and iterations since the mid-70's, and is basically the MTA on the internet. The good part is that at this point there are no real vulnerabilities common to all versions of sendmail, so a Sun box is not likely to have the same exploit as an AIX box at the same time, etc.

In this way it is kind of like BIND, while there have been all kinds of exploits for it over it's lifetime, there has yet to be an alternative that can provide the same or better service with less security risk.

As for IMAP, it is not really all that insecure by nature, but as with all daemons it has had it's share of vulnerabilities. Also, the same applies to IMAP as does any of service; the specifics of the vulnerability are usually in the implementation and isolated to one vendors version.

[slarty]

Originally posted by spurious_inode
Fun for the whole family ...
I'll leave it up to your imagination as to how you can have fun with this little
feature in sendmail. [/B]

It is not a bug, it's a feature. Any MTA would do the same.

You don't understand. Internet email has no authentication on the sender, so email servers *have* to trust and accept any email which looks vaguely plausible.

"Vaguely plausible" varies from site to site, needless to say it's not usually very difficult to make it sound plausible. Usually all that's required is an originating address in a domain that exists and the target doesn't know any better.

It cannot possibly distinguish you from the mail relay from foo.net - so it has to accept the message.

[spurious_inode]

Originally posted here by slarty
It is not a bug, it's a feature. Any MTA would do the same.

Great point Slarty, .... oh yeah that's right, I actually said:

I'll leave it up to your imagination as to how you can have fun with this little feature in sendmail.

I didn't call it a bug, I called it a feature. Then I was corrected and told that it is not a bug, it's a feature. hmmmmmm.....

Your right, MTA's will do this because in the example given the commands manually step through the process of one MTA delivering mail to another. This does not take away from the fact that it is still fun to do.

Quick to succor and slow to flame I always say. I'll just chalk this one up to good intentions.

Thanks Slarty.

[ConsummatumEst]

When I first got into computer security, I remember sendmail being the joke of the industry. Sendmail has a very spotty past in the computer security world. It's reputation then is probably comparable to IIS's reputation today. Lots of people use it, but no one ever really trusts it. In the past few years, though, it seemed like the folks who develop sendmail had learned from past mistakes and sendmail was actually beginning to look like a fairly secure product. Then someone went and found two serious exploits in under a month and any illusions I had were shattered. I guess it's time for me to take another look at Qmail et al.

[Mizo]

what i suggest ist most simple thing , just go to www.download.com and download a mail server ! u can host it at your own pc and send and deliver mails . and u can secure your home pc better :>>> and those web -based mails ... sorry but sux !

Mizo

Knowlege is like fountain, students are there to drunk! :>>>

[smirc]

Sendmail has been around for a while and has a reputation for having more holes than Swiss cheese. This is probably unfair since it has always been one of the most popular deamons used on the Internet, and so has had plenty of time for people to test it's security. Sendmail also took a major blow after the 1998 Morris worm crippled the Internet using a sendmail exploit.

Sendmail is also highly configurable which can be a good thing but it also makes it very hard to secure. If you want an idea of just how configurable sendmail is, it is the only mail deamon that I've ever heard of that can be reconfigured to effectively run as a web server, which is obviously not it's intended use. No I'm not making this up.

When you think about it though, just about every major deamon has root exploit vulnerabilities found in the source including bind, wuftpd, proftpd, apache and dhcpd but has this stopped them from being the most popular deamons for their respected services? Not really.

The fact is, CERT has given network administrators the opportunity to effectively neutralise the impact of most root expoits because they can be patched relatively quickly allowing only a small window of opportunity for the kiddies to exploit new found bugs to their advantages. Zero day exploits are not all that common and are usually given high priority and fixed quickly. I'd be more worried about how quick my administrator is to apply patches and configure services properly, rather than the type of software being used.

Having said this there are those people with less than honourable intentions who find security holes, don't report them and use them to their advantage. But these sorts of people aren't your average script kiddies. They know what they're doing and don't feel the need to advertise their activities. If they really want to get into your system, they will, sendmail or not.

[vescovono]

We have used sendmail for years, and work to keep it up to date for security. It's like any kind of software or program, it needs to be maintained. Here are some of the more recent issues we are working on:

http://www.cert.org/advisories/CA-2003-07.html

http://www.cert.org/advisories/CA-2003-12.html

The problem being that with any of these alerts, we have to investigate and test the solution before we roll out into production and have to be especially weary of any patches that would overwrite sendmail.cf (HPUX) as we have modified that file for our use.

Also - these are listed in the advisories, but in case you just want these links and don't have them:

http://www.sendmail.com/security/

http://www.sendmail.org

Sendmail is a target, but it has worked for us since at least '96 so again, not the best, but it can be fixed... and fixed... and fixed.