Solaris Telnet 0-day vulnerability

philos writes "According to SANS ISC, there's a vulnerability in Solaris 10 and 11 telnet that allows anyone to remotely connect as any account, including root, without authentication. Remote access can be gained with nothing more than a telnet client. More information and a Snort signature can be found at riosec.com. Worse, this is almost identical to a bug in AIX and Linux rlogin from way back in 1994."

Comments

Why is this a big deal?

[nettdata]

Who the hell even THINKS about enabling telnet on any box these days?

Re:Why is this a big deal?

[TheGratefulNet]

nothing WRONG with telnet. I use it all the time.

but ONLY on trusted lans, of course.

I find it quicker than ssh logins. of course its quicker, it has no encryption to do. and the initial seeding (at connect time) also takes a LONG time on some boxes (ssh to a cisco box; come back after lunch and you'll get your login prompt).

telnet over a wan is dumb. telnet over a 10' piece of wire is NOT dumb.

telnet has its place.

Re:Why is this a big deal?

[drsmithy]

Who the hell even THINKS about enabling telnet on any box these days?

Sun, apparently, since it's enabled by default.

Re:Why is this a big deal?

[imikem]

Relevant line from /etc/services:

telnet 23/tcp imadumbass hackmenow rootrus rotflmao

Re:Why is this a big deal?

[teslar]

I do. And then I sit down naked in the snow and castigate myself with a 9-tail as a punishment for these impure thoughts.

Having said that, today is a good day to find out if that head of IT you never liked anyway has telnet enabled on one of his Solaris machines :)

Re:Why is this a big deal?

[SatanicPuppy]

Telnet is dumb! Quicker than SSH? What the hell? Are you streaming video over your SSH connection or what? Most sane people just use it for a remote console, and speed isn't much of an issue in those circumstances...

Opening/enabling telnet is a mistake. Even if you're using it safely, which, in my mind, is across a hub that isn't connected to anything else but the two computers you're talking to you've still got that port open and vulnerable. Using it on a LAN is just begging someone with a packet sniffer to come along and steal your user info.

Re:Why is this a big deal?

[Nasarius]

Quicker than SSH? What the hell? Are you streaming video over your SSH connection or what?

I think GP is referring to the initial connect handshake. Oh no, it takes an extra 500ms to establish a secure connection. If your network is private enough to feel safe using telnet, you can certainly set up RSA/DSA keys to use SSH without a password, eliminating the time it takes to enter it.

Re:Why is this a big deal?

[bockelboy]

Let me take a crack at this:

1) Fermi National Accelerator Laboratory.

That'll account for a couple thousand computers. It's left as an exercise for the reader to find other sites.

Are they just crazy? I know that almost every single box at FNAL has the telnet daemon running, and is behind no firewall. Why aren't they hacked-to-death? Kerberos.

FNAL has a policy that every service beyond central IT's web pages is protected by Kerberos. The Kerberos-enabled version of telnet is as secure as one can get; I've been told by their sysadmins that it is more secure than SSH because it is simpler and the network and authz/authn stacks are separated. So, historically, Kerberos-enabled telnet has had less bugs than SSH.

Just because YOU don't run telnet (or don't know how to run it securely) doesn't mean that there aren't thousands of boxes out there that are secured by it.

If there are actually any Sun boxes at FNAL (they were one of the original big adopters of Linux), you can bet they'll probably be turned off today...

Re:Why is this a big deal?

[mi]

If ssh on your cisco boxes is slow, you either have serious network problems [...]

Most likely, the reverse DNS is misconfigured. This is the number one reason for ssh-login delays. Maybe, the nameservers initially put into the router's configuration are no longer reachable due to subsequent "hardening". Or, maybe, they went away and were replaced long ago — without anybody telling the routers. Nothing else on a router uses DNS usually, so this problem affects only ssh-daemon and gets blamed on it...

The daemon could, of course, be a little bit smarter and not try to do a reverse DNS, when there are no hostname-based authorization rules in the first place... But that's a minor bug compared to reverse DNS being dysfunctional.

Re:Why is this a big deal?

[dknj]

except it's not... (at least not as of the 10/06 release)

Re:Why is this a big deal?

[99BottlesOfBeerInMyF]

Who the hell even THINKS about enabling telnet on any box these days?

Sadly, a whole lot of people. I work for a company that makes very expensive and cool specialty servers that perform certain security related functions. As a security company, naturally we take care not to tarnish our reputation by leaving these servers vulnerable themselves. We try to encourage our customers to be moderately responsible as well, as any box can be made insecure. I know of at least on tier-1 ISP that has one of our boxes sitting publicly accessible with telnet enabled and no IP access restrictions.

As for who uses telnet in general, most ISPs in Asia seem to use telnet to configure their systems via their control networks. Large financial institutions in Europe use telnet, as use of encryption is restricted on their trusted networks, for reasons of transparency to the stock regulating authorities. ISPs in South America often use telnet and provide shell accounts to customers. I'm sure there are more groups that use it for one reason or another.

Re:Why is this a big deal?

[SatanicPuppy]

Sounds like they're more interested in watching their own employees than in securing their systems from external threats.

If it were me I'd just log everything in every session (which is easy), and make the users use SSH. That way you can audit everything they do, every command they type, but still have a level of security. You have to remember that any user can sniff telnet traffic on the network, so forcing everyone to use telnet because you don't trust them means the ones who are untrustworthy have a better chance of stealing something useful from a coworker.

Even better would be to hire trustworthy people and treat them as such in the absence of evidence to the contrary.

Re:Why is this a big deal?

[jaymzter]

I have 11/06, and believe me, I was surprised to find telnet enabled.

Re:Why is this a big deal?

[arth1]

Since the exploit site didn't yet have information about older versions of Solaris/SunOS, I hope it can quench the panic for some when I say that only Solaris 10+ appears to be affected.

If you're on Solaris 8 (SunOS 5.8 or Solaris 2.5.8) or 9 (SunOS 5.9, or Solaris 2.5.9), you appear to be safe.

This is relevant because large companies seldom jump to the newer versions until they have to - for production systems, as long as the older versions are supported and working, that's more important than gambling on existing software still working if upgrading the OS. So there's an awful lot of systems with Solaris 8 and 9 out there, but luckily they appear not to be affected.

Re:Why is this a big deal?

[arth1]

Vendor support for ssh is one factor. Many companies have aversions to installing software unless it's backed by FULL support from the vendor. Having to go to a third party, like F-Secure, to get vendor support is often undesirable, and unfortunately, security can lose to support requirements, service level agreements and response time. Even worse is that there's multiple and sometimes incompatible versions of SSH out there - what may come with one system isn't guaranteed to work with another.
Can you get the OS vendor to jump and have a man there within 30 minutes to fix it if a supported OS function doesn't work? Yes. Can you get the OS vendor to jump and have a man there within 30 minutes if OpenSSH doesn't work? No. Sometimes it's as simple as that, unfortunately.

That said, don't think that I believe telnet is a good substitute for ssh, but often, and especially in a turtled environment (hard on the outside, soft on the inside) where five nines are more important than internal security, it may still be a better choice, at least until all the OS vendors provide fully supported (and compatible!) versions of SSH.

Re:Why is this a big deal?

[bugnuts]

Security best practices are the same whether you're talking about securing your home network or a military network No. It's not. The only thing those have in common is considering what you are protecting, and how much risk you wish to take versus the convenience granted. The specifics are immaterial.

The OP is right, he knows his risks and has deemed it acceptable. You and others, having no idea of the risk, deem it unacceptable and are the ignorant ones.

Re:Why is this a big deal?

[evilviper]

Just because the login is "safe" doesn't mean that using an unencrypted protocol is ever a good idea.

You're right... No more secure websites for you, since HTTPS is just HTTP over an SSL data stream.

You could just as easily use Kerberos to encrypt HTTP traffic as SSL, and that is indeed exactly what Kerberos does for just about any communications protocol...

Kerberos telnet is as encrypted as it gets.

Re:Here come the fanboys

[SatanicPuppy]

Just because it's not deployed in many places, doesn't mean that those places aren't cracker dream targets...I've got 5 Solaris machines, and the least critical of them is a far better target than the most critical Windows, or even Linux box.

Still, first poster is right. Wtf uses telnet anymore, unless they're dealing with the most legacy of legacy crap.

not an excuse

[otacon]

"Nobody should be using it anyways" is not an excuse. If it is included, it should be held to the same standard as every other application. In some legacy cases I'm sure telnet is of some use. But regardless the fact that it has a practical use or not is irrelevant.

the authors seem very confused ...

[petes_PoV]

First they say there's a bug with telnet passing switches through to login.
Then they start a tirade against sending passwords in the clear.
After that they say the fix is not to use telnet.

Putting aside the holier (more secure) than thou attitudes here about telnet security. I've got to say that not using something because it's broken is never a fix (unless you're a manager). The fix is to mend the problem. In the meantime, maybe, avoid the service. but bear in mind, someone still has to fix it.

Re:Telnet?

[Anonymous Coward]

Solaris 8, 9, 10 -- all have telnet, ftp, rlogin and others enabled by default at a clean install.
You can check it for yourself in vmware, if you do not believe.

Who uses telnet these days?

[deevnil]

towel.blinkenlights.nl, that's who.

Re:Configuration issue

[walt-sjc]

Since apparently Sun is negligent enough to have telnet enabled by default, it is an important story. This reminds me of the old NT4 days, where every service on the machine was enabled by default, and the first thing you had to do was turn everything off. Come on Sun, get with program here...

Re:0-day?

[walt-sjc]

No, zero day means that an exploit was released before or on the same day as the vendor / community found out about it. Ethical security researchers notify the vendor first, and at LEAST give them a few days / weeks to resolve the problem before releasing the full details to the public.

Re:Here come the fanboys

[SatanicPuppy]

Sure, but that's not what's being discussed. There is a world of difference between using telnet to fake some other non-encrypted protocol, and leaving the telnet service enabled on your machine.

The Exploit

[biftek]

Since noone seems to have bothered posting it yet, "telnet -l -frandomuser randomsolarishost".

So stupid.

Re:Configuration issue

[zdzichu]

The article talks about Solaris 10 u1 released in 2005. The latest thing is u3, which has two things:

1) this attack does not work:

Escape character is '^]'.
Not on system console
Connection closed by foreign host.

2) when installing U3 one can opt to close most services. This could be also done after installation with "netservices limited" command.

Didn't work on Solaris 10 01/06

[jaymzter]

rhlinux1:~$ telnet -l"-froot" solaris
Trying 172.16.141.27...
Connected to solaris.example.com (172.16.141.27).
Escape character is '^]'.
Not on system console
Connection closed by foreign host

This is basically a vanilla install.

Re:Didn't work on Solaris 10 01/06

[Anonymous Coward]

telnet -l"-fbin" solaris

Re:Configuration issue

[moyix]

This is only because root is not allowed to log in remotely by default. "-fanyotheruser" will still work. I believe the current favorite is "-fbin". Also, if you've commented out the console line in /etc/default/login, it will allow access to root.

This has been confirmed on the latest version of Solaris 10.