More MS06-042 woes

Published: 2006-08-22
Last Updated: 2006-08-22 23:35:49 UTC
by Johannes Ullrich (Version: 1)
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The hotfix for MS06-042, which was supposed to be released today, has been delayed. Worse: It turns out that MS06-042 introduced a new security problem. The crashes everyone is having so much fun with are just the tip of the iceberg. The issue can also be used to execute arbitrary code. In particular, note that MSFT's advisory essentially tells you how to exploit the issue. Exploits will likely follow very soon (days?).

At this point, we recommend:
  • Keep MS06-042 applied if you can. It fixes more bugs than it creates.
  • If you are having problems with internal web sites that can no longer be used: Restrict MSIE to be used internally only.
  • Use Firefox/Opera or other browsers for now.
  • "SandboxIE" can be used to protect your system from damage caused via MSIE.
  • If you establish a "No MSIE" policy, you can use the snort rule below to detect accidental policy violations.
Snort Rule:
alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS \
(content: "|0D 0A|User-Agent\: Mozilla/4.0 (compatible\; MSIE 6.0";)
Links: (updated patch matrix) (EEye Alert regarding the code execution) (MSRC blog article regarding MS06-042 issue, dated Aug. 16th). (latest MSRC blog)

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Microsoft August 2006 Patches: STATUS

Published: 2006-09-11
Last Updated: 2006-09-11 23:05:04 UTC
by Swa Frantzen (Version: 13)
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Overview of the known problems and publicly known exploits ofthe August 2006 Microsoft patches.

# Known Problems with this patch
Known Exploits
client rating server rating
MS06-040 Issue with:
  • Huge memory allocations on Windows 2003 server SP1 (32bit & 64bit), XP (64bit) and 32bit application.
  • Microsoft Business Solutions?Navision 3.70 on above platform.
  • Websense Manager when using terminal services
  • Hotfix available by calling Microsoft.
More information:
Botnets actively exploiting this in  the WILD

Exploit available in easy to use package

MS06-041 No reported problems

Critical Critical
MS06-042 Critical issue:

  • This patch introduces a new arbitrary code execution vulnerability on MSIE 6 SP1.
  • Microsoft re-released MS06-042 on Aug 24th 2006.
  • It is unclear if the hotfix that was available earlier fixes this problem as well.

More info:

Issue #1:
  • MSIE 6 SP1 crashes while using multiple application such as Peoplesoft, Siebel, Sage CRM and websites using HTTP 1.1 and compression such as the register.
  • Roll-up patch so it has all older issues as well.
  • Workaround to disable HTTP/1.1
  • Use alternate browser (for problem sites)
  • Upgrade to MSIE 6 SP2
  • The re-release of the August 24th is intended to fix this. The fix was supposed to be published by Microsoft on August 22nd, 2006 but was delayed.
More Information:
Issue #2:
  • CA Unicenter Service Desk can cause MSIE to crash, on XP SP2 and Windows 2003 SP1
  • Use the supported Firefox or Mozilla browsers
  • KB923996
  • The re-release of MS06-042 is not fixing this problem as far as we know.
More information:

Original MS06-42: fixes a.o. a  FTP vulnerability that;s well-known since 2004

First revision of the MS06-042  patch's buffer overglow has details public.
  • Microsoft released it first on the 22nd
  • actual code fragments were publicly released on the 24th after the patch was updated
MS06-043 No reported problems
Important Less urgent
MS06-044 No reported problems
Critical Critical
MS06-045 No confirmed problems
Critical Less urgent
MS06-046 No reported problems
Critical Important
MS06-047 No reported problems Trojan dropper reported in word document by Symantec, Trendmicro(1) and Trendmicro(2).  The dropper loads a backdoor: Trendmicro, Symantec

See also diary.
Critical Less urgent
MS06-048 No reported problems Trojan dropper in Powerpoint Critical Less urgent
MS06-049 Unconfirmed reports about corruption of files on compressed volumes.
[Windows 2000 only patch]

Less urgent
MS06-050 No reported problems
Critical Important
MS06-051 Although unconfirmed by Microsoft so far, there seem to be problems related to Terminal Services and multiple users loading certain DLLs as part of some applications. Details and fixes or workarounds are too sketchy so far.

See also the problem with .ini files and citrix at the citrix support forum.

We're still lookign for a more detailed discription of the problems.

Critical Critical

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
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Tip of the Day - PHP Security

Published: 2006-08-22
Last Updated: 2006-08-22 15:12:14 UTC
by Johannes Ullrich (Version: 2)
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For all of us here coding in PHP (Motto: Input validation is for people who can'tdo forensics), I put together a couple of configuration tips to provide an extra layer of security. Now while all of your own applications are of course bug free and will never get exploited, you just may have to use some third party code once in a while.

php.ini choices:

The following options should be no-brainers and are the default choices for current php installs:
magic_quotes_gpc = On
register_globals = Off
The first option will automagically escape all quotes, taking essentially care of 90% of your SQL injection worries. The second part will prevent creative users from adding their own variables without you explicitly requesting them. Extra super secret tip: You probably want to get rid of any php application that breaks after you turn off register_globals. 

For some extra credit, you can play with 'safe_mode'. But read the instructions carefully. safe_mode is something you best enable before starting to code, as it can be tricky to enable it for an existing application.

/tmp partition:

Most php exploits need a bit of space to pull down additional code. Now we don't allow our web server to write files just anywhere. But if you are an exploit, you always got /tmp to use as your "scrap space". Probably the most effective defense against php exploits is to make /tmp its own partition and make it non executable. (and while you are at it, read Swa's tip about mount options). Don't forget to make /usr/tmp and /var/tmp a symlink to /tmp. Any other directory that has to be writable by Apache should be placed on this partition. You don't have to repartition your system. Just use a loopback file.


The two tips above should protect you from most of the automated codes thats running around the net these days with not too much effort on your side. After all, you need to get back to coding quickly. So how do you keep the more pesky little kids aways from exploring the underbelly of your applications? Now this is where a little bit of IDS and automated response can go a long way. First of all, lets talk dirty for a bit: robots.txt. As the name implies, robots.txt is for 'bots. But then again, some web developers associate magic powers with it and expect it to cloak all files listed in it from all bad influences. Now yes, this may be true. But did you use the key stroke associated with "magic spell" as you edited the file in vi? If not: your files are still all visible and robots.txt can provide a roadmap to an attacker. Consider this robots.txt file pulled from some random website:
User-agent: *
Disallow: /adminpage.php

Now where would you go today attacking this website?

Simple lesson: Add a good looking file like this to your robots.txt file, with a little twist: "adminpage.php" should not unlock all your secrets. Instead, have it send you a quick e-mail and maybe have the IP added to a shun-list if this page is hit. (Extra credit: Find out how to get yourself locked out of for the next week... so no playing in the dirt while pretending to wear a white hat).

More Extra Credit:

We all love extra credit. So here a couple more pointers:
  • chrooting apache/php. Not for everyone, but a very nice extra layer. Quick tip: If you still want to send email from php, look for a program called mini_sendmail.
  • mod_security. very nice IDS/IPS style extension for Apache.
  • swatch to monitor your log files.
  • disable extensions you don't need.
And now its time for our commercial break. If you want to know more about securing MySQL, Apache and PHP, see me in Vegas in October.

Reader additions:

Richard recommends "mod_evasive" as another Apache module to consider:

"In addition to mod_security (which I think is tricky to configure well) I'd recommend mod_evasive. This tool which used to be called mod_dosevasive blocks any IP that makes too many identical requests. For pages that are CPU intensive (which PHP often is) blocking these requests can be a big win."

Sounds like a nice idea.

Daniel writes:

"Some other hints:
Also one of the moist exploited PHP functions which should be disable by default: allow_url_fopen."

In order to disable "allow_url_fopen", check for this line in php.ini:
allow_url_fopen = Off

Of cource, there may be applications that require this feature.

Johannes Ullrich.

Keywords: ToD
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