Today´s Diary

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Published: 2008-05-13,
Last Updated: 2008-05-13 17:59:16 UTC
by Swa Frantzen (Version: 1)
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Overview of the May 2008 Microsoft patches and their status.

# Affected Contra Indications Known Exploits Microsoft rating ISC rating(*)
clients servers
MS08-026 Multiple vulnerabilities allow code execution when opening a malicious file. Files opened with word and edited with word in outlook are of particular concern.
Replaces MS08-009.
Office

CVE-2008-1091
CVE-2008-1434
KB 951207 No publicly known exploits Critical Critical Important
MS08-027 The fixed vulnerability is an input validation failure leading to memory corruption and code execution.
Replaces MS08-012 and MS07-037.
Publisher

CVE-2008-0119
KB 951208
No publicly known exploits Critical Critical Important
MS08-028 The fixed vulnerability is an input validation failure leading to a buffer overflow and allowing code execution.
Jet database engine

CVE-2007-6026
KB 950749

SA 950627
Actively exploited Critical PATCH NOW Important
MS08-029

Microsoft onecare, antigen, defender and forefront use the malwware protection engine. It suffers from multiple input validation failures leading to a Denial of Service.

Microsoft malware protection engine

CVE-2008-1437
CVE-2008-1438

KB 952044
No publicly known exploits Moderate Less Urgent Important

 

We will update issues on this page as they evolve.
We appreciate updates
US based customers can call Microsoft for free patch related support on 1-866-PCSAFETY
(*): ISC rating
  • We use 4 levels:
    • PATCH NOW: Typically used where we see immediate danger of exploitation. Typical environments will want to deploy these patches ASAP. Workarounds are typically not accepted by users or are not possible. This rating is often used when typical deployments make it vulnerable and exploits are being used or easy to obtain or make.
    • Critical: Anything that needs little to become "interesting" for the dark side. Best approach is to test and deploy ASAP. Workarounds can give more time to test.
    • Important: Things where more testing and other measures can help.
    • Less Urgent: Typically we expect the impact if left unpatched to be not that big a deal in the short term. Do not forget them however.
  • The difference between the client and server rating is based on how you use the affected machine. We take into account the typical client and server deployment in the usage of the machine and the common measures people typically have in place already. Measures we presume are simple best practices for servers such as not using outlook, MSIE, word etc. to do traditional office or leisure work.
  • The rating is not a risk analysis as such. It is a rating of importance of the vulnerability and the perceived or even predicted threat for affected systems. The rating does not account for the number of affected systems there are. It is for an affected system in a typical worst-case role.
  • Only the organization itself is in a position to do a full risk analysis involving the presence (or lack of) affected systems, the actually implemented measures, the impact on their operation and the value of the assets involved.
  • All patches released by a vendor are important enough to have a close look if you use the affected systems. There is little incentive for vendors to publicize patches that do not have some form of risk to them.

--
Swa Frantzen -- Gorilla Security

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Published: 2008-05-13,
Last Updated: 2008-05-13 17:26:44 UTC
by Swa Frantzen (Version: 1)
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Debian and Ubuntu Linux users should look into their OpenSSH setup. It turns out the used PRNG (Pseudo Random Number Generator) used was predictable.

Remember patching isn't enough, you need to regenerate keys generated on these machines! Including those used in SSL certificates (X.509).

Worse: even good keys apparently can be exposed due to this. Quoting from the Debian reference below:

"Furthermore, all DSA keys ever used on affected Debian systems for signing or authentication purposes should be considered compromised; the Digital Signature Algorithm relies on a secret random value used during signature generation."

So merely using your (good) keys on an affected machine might be enough to get the key itself compromised.

--
Swa Frantzen -- Gorilla Security

Keywords: linux openssh
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Published: 2008-05-12,
Last Updated: 2008-05-13 10:27:43 UTC
by Scott Fendley (Version: 3)
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Greetings everyone.  Just a bit of a reminder that many colleges and universities are done for the spring semester, and the K12s are right around the corner.  As most of you already realize, this means that a number of very intelligent kids and young adults are soon to have far more free time on their hands (and less adult supervision during the normal working hours for their parents).  So I expect that there will be a bit of an increase of attacks and other general noise from outside of corporate or campus network as we have observed in prior years.

In that frame of mind, there has been a significant amount of brute force scanning reported by some of our readers and on other mailing lists.  And there does appear to be a bit of a spike reflected in the port 22/tcp sources in the past week in the Dshield data.

Jim Owens and Jeanna Matthews of Clarkson University released a paper which investigates current methods and dictionaries used by attackers of SSH in the past several months.  The paper shows some evaluations of common techniques used to defend against brute force attacks that are worth reading to some.

From the most recent reports I have seen, the attackers have been using either ‘low and slow’ style attacks to avoid locking out accounts and/or being detected by IDS/IPS systems.  Some attackers seem to be using botnets to do a distributed style attack which also is not likely to exceed thresholds common on the network.

So be warned that there does appear to be a bit more activity involving SSH and weak or otherwise guessable passwords.  This would be a great time to do some investigation on your local network to see what servers have SSH open to the world on the default port, and may need to have its security posture reassessed.  You might want to try using a few of the techniques discussed in the paper by Owens and Matthews such as

  • Using the host based security tools of DenyHosts, fail2ban, or BlockHosts in conjunction with TCP-Wrappers to block access to servers across your organization.
  • Disable direct access to the root account.
  • Avoid using easily guessed user names such as only a first name or a last name.  (Side Note: Academia will need to look into the age old policy of publishing an online directory of account holders before this one will have much of an effect.)
  • Enforce strong passwords or use public key authentication in place of passwords (multi-factor or public key is the preferred method especially for systems which contain sensitive data) .
  • Generally reduce the number of publicly accessible services through iptables or similar host based security measures in addition to network firewalls.  (think defense in depth.)

You might note that there is one defense technique that was not even mentioned in the paper, or was not recommended by me.  That technique is to lock accounts after X number of failed login attempts.  As I work in a similar environment as the authors, I can tell you that this technique has numerous issues when working with academia.  First and foremost, the potential for creating a denial of service issue must be weighed against the potential of attackers guessing the right password before IT Security notices.  The likelyhood of having a student take out their frustration for a non-IT related issue on a professor or an ex-boyfriend or girlfriend is actually very significant.  Additionally, having a single sign-on infrastructure used from Web Applications, Unix based apps and interface, and windows based services mean you have to do significant synchronization of information to make this technique effective against distributed and/or slow attacks.    Your mileage for using this  technique may vary and could be more valid in your environment.

Thanks to all of the readers who have already sent in their observations to us today.  :-)

Update 1:
One of our handlers, Jim, pointed me to the DenyHost stat site located at http://stats.denyhosts.net/stats.html.  As already mentioned, this does appear to be a significant new trend of which we all should be aware.

Another one of our readers sometimes gives advice/consults for an organization which today was having problems with a server denying access to anyone attempting to connect. The reason was that Sshd was denying all connections due to too many failed login attempts.  It was recommended that internal servers could use the default port, but external facing hosts which have a need for ssh should use a non-standard high port.  Yes, itt is a form of security by obscurity, but it does defeat brain-dead brute force attacks.

Keywords: bruteforce ssh
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Published: 2008-05-12,
Last Updated: 2008-05-13 00:04:19 UTC
by Scott Fendley (Version: 2)
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Last week, Adobe released a security bulletin concerning updates that should be deployed as a part of your normal patch procedures earlier this year.  The updates available at Adobe.com address vulnerabilities which could cause Adobe Reader or Acrobat applications to crash or even allow an attacker to take control of the affected system.   More details about this set of updates is available at http://www.adobe.com/support/security/bulletins/apsb08-13.html.

If you haven't already done so, I recommend that this update be added into the mix of testing and deployment along with the Windows Updates to be released on Tuesday.  MacOSX users should also update to either Acrobat 7.1.0 or version 8.1.2 at the earliest convenience as well.

Keywords: Adobe
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Diary Archive

DateAuthorTitle
2008-05-13Swa Frantzen May 2008 black tuesday overview
2008-05-13Swa Frantzen OpenSSH: Predictable PRNG in debian and ubuntu Linux
2008-05-12Scott Fendley Brute-force SSH Attacks on the Rise
2008-05-12Scott Fendley Adobe Releases Security Updates
2008-05-11David Goldsmith Mass File Injection Attack
2008-05-09Joel Esler Thunderbird 2.0.0.14 is out!
2008-05-08Joel Esler COMPROMISED FILE IN VIETNAMESE LANGUAGE PACK FOR FIREFOX 2
2008-05-07Jim Clausing More on automated exploit generation
2008-05-07Jim Clausing OSSEC 1.5 released
2008-05-06John Bambenek Windows XP Service Pack 3 Released
Complete Archive
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