Microsoft April 2012 Black Tuesday Update - Overview

Published: 2012-04-10
Last Updated: 2012-04-11 01:57:49 UTC
by Swa Frantzen (Version: 1)
8 comment(s)

Overview of the April 2012 Microsoft patches and their status.

# Affected Contra Indications - KB Known Exploits Microsoft rating(**) ISC rating(*)
clients servers
MS12-023 Cumulative update for Internet Explorer adding fixes for 5 more random code execution vulnerabilities with the rights of the logged-on user.
Replaces MS12-010.

KB 2675157 No publicly known exploits. Severity:Critical
Critical important
MS12-024 An input validation vulnerability in the parsing of the signatures on executable files allows random code execution with the rights of the logged on user.
Replaces MS10-019.
Windows Authenticode

KB 2653956 No publicly known exploits. Severity:Critical
Critical Critical
MS12-025 An input validation failure in the .NET framework allows random code execution with the rights of the logged on user. This not only affects users browsing websites but also IIS servers running ASP.NET in e.g. a web hosting scenario.

KB 2671605 No publicly known exploits Severity:Critical
Critical Critical
MS12-026 Vulnerabilities in Forefront UAG (Unified Access Gateway) allow unfiltered access to internal resources and spoofing of the UAG webserver (directing the visitor to malicious sites instead of the UAG server, potentially compromising their login credentials).
Forefront UAG

KB 2663860
No publicly known exploits Severity:Important
NA Critical
MS12-027 A vulnerability in Windows Common Controls [ActiveX] allows random code execution with the rights of the logged-on user. Attack vectors include websites and email attachments. Also affects a whole lot of other Microsoft software such as SQL server, Commerce Server, Visual FoxPro, Visual Basic runtime aside of Microsoft Office.
Windows Common Controls

KB 2664258
Microsoft claims to be aware of "limited targeted attacks" using this. Severity:Critical
Critical Important
MS12-028 An input validation vulnerability in the .wps converter allows random code execution with the rights of the logged on user.
Replaces MS09-024 and MS10-105.
Office - works

KB 2639185
No publicly known exploits Severity:Important
Critical Important
We will update issues on this page for about a week or so 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.

(**): The exploitability rating we show is the worst of them all due to the too large number of ratings Microsoft assigns to some of the patches.

Swa Frantzen -- Section 66

NOTE: These security updates also included an update for Windows 8 Customer Preview.   Updates for Windows 8 are available through the operating systems Windows Update. (Thanks Rene! - Mark Baggett)

8 comment(s)


After giving you a hard time on the Vista post, Swa, I have to give you kudos for these Black Tuesday updates. We'll done and informative; I reference them in our patch management testing and communications. Thx.
Anyone know why this is going on?:
- - OK...
"502 - Web server received an invalid response while acting as a gateway or proxy server.
There is a problem with the page you are looking for, and it cannot be displayed. When the Web server (while acting as a gateway or proxy) contacted the upstream content server, it received an invalid response from the content server."
I don't think MS12-024 rates a "Critical", at least based on what I see in the bulletin. In a nutshell, the authenticode validation on the EXE is crackable. From the bulletin:

How could an attacker exploit the vulnerability?
Exploitation of this vulnerability requires that a user or application run or install a specially crafted, signed PE file. An attacker could modify an existing signed file to include malicious code without invalidating the signature. This code would execute in the context of the privilege in which the signed PE file was launched.

Back to me. I don't see any evidence in the bulletin that verifying the authenticode signature is sufficient for code execution (which would be a Critical because it would mean that merely inspecting properties on an EXE could trigger code execution), but merely that an attacker can fake the authenticode signature on a malicious EXE. Yes, that's bad, but that implies that the attacker has already convinced you to download their malicious EXE or managed to get it onto your system. And that they've convinced you to do that, but you're the sort of person who checks those authenticode signatures and relies upon them. The intersection of people who run arbitrary EXEs from potentially unknown sources and who then check authenticode signatures is pretty small! I can see how it might be bad if someone manages to spoof the Microsoft content distribution network and send out malicious patches, but that'll take some work to set up.
@Anonymous: you make a valid point I think. I reread the entire bulletin just now and there are two nagging things I saw:
- first I'm not sure there isn't messing with the signature itself to create a problem as well as the ability to add stuff outside of the signed data.
- secondly MSFT mentions that *installing* a crafted PE could lead to exploitation (as an alternative to executing it). This could mean that an admin installing something for a user lacking admin rights could be hit ? Merely by installing it, not even executing it...
Anyway I've asked Microsoft for clarification on just what scenarios allow the execution of unsigned code. Let's hope they respond soon.
IMO MS12-024 is highly critical because update processes (Windows itself, anti-virus and applications) usually depend on signed executables that are typically transferred "in the clear" (mostly using http).

The way I read it, anyone with access to such files, either on (intermediate) servers or by tapping the "wire" (think public WiFi hotspots) will be able to invoke this vulnerability and compromise PC's of unsuspecting users.

It would be interesting to know whether just _checking_ the signature (right click on the file, Properties, Digital Signatures, select line, click Details) invokes this vulnerability. However such information probably also benefits potential attackers.
The problem is when a JAVA exploit gains control and installs code. If it is okay and signed correctly no warning will pop up. The code with a false signature WILL execute without UAC popping up at all without this patch installed. Tha tis the vulnerability. Best, Al
Just an "FYI"... the
... is apparently fixed - 'nice timing for it to have gone belly-up.

Unable to Print TurboTax Return After Installing the Latest Windows
Update (Last Updated 12 Apr-12)
Seeing issues with Turbotax printing after this week's updates. US Tax filing day is Tuesday.

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