MS12-020 RDP vulnerabilities: Patch, Mitigate, Detect

Published: 2012-03-16. Last Updated: 2012-03-17 23:46:10 UTC
by Russ McRee (Version: 1)

As a follow up to the fact the we've raised the INFOCON level to yellow for MS12-020, a step not taken lightly, it was suggested that we offer a few simple things folks can do to ensure that they're patched appropriately, as well as employ possible mitigations and detection.

Specifically, MS12-020 includes KB2671387 (Remote Code Execution - CVE-2012-0002) and KB2667402 (Denial of Service - CVE-2012-0152) or KB2621440.

The reference for the update you'll see on a Windows system, when installed, depends on the version of the OS you're running. For Windows 7 you'll likely note KB2667402, whereas you should only expect KB2621440 on a Windows XP host.

Confusing, I know, but it matters. Read the full MS12-020 bulletin to confirm.

The simplest step to determine if you're properly updated, using Window 7 x64 as an example is:

Start -> All Programs -> Windows Update -> View Update History and look for reference to KB2667402 as seen in Figure 1.

Figure 1

If on a Windows XP host, using Microsoft Update, you can opt for Start -> Microsoft Update -> Review your update history and ensure KB2621440 is installed.

Additionally, at the command prompt, you can use Windows Management Instrumentation Command-line (WMIC) and issue:

wmic qfe | find "KB2667402" or wmic qfe | find "KB2621440"

If patched you'll note results as seen in Figure 2.

Figure 2

Mitigation

Per the bulletins, "systems that do not have RDP enabled are not at risk."

Your privileges on a given system (enterprise GPOs may prevent changes) may dictate your level of success.

Options include, aside from the obvious (PATCH):

1) Don't run RDP if you don't really need it.

Start -> Run -> services.msc -> Stop and/or disable Remote Desktop Services (Figure 3) or disable it via Control Panel

Figure 3

2) Use Windows Firewall (where applicable and if enabled) to prevent access to RDP (Figure 4)at the host level

Figure 4

3) Ensure your network security configurations don't unnecessarily allow RDP (TCP 3389) from the Internet. If you absolutely, positively must do so, restrict it to approved hosts.

4) Enable Network Level Authentication (NLA) on Vista and later systems. Per the SRD blog: "On systems with NLA enabled, the vulnerable code is still present and could potentially be exploited for code execution. However, NLA would require an attacker to first authenticate to the server before attempting to exploit the vulnerability."

Detection

Snort users can keep an eye on the likes of Emerging Threats. A rule (SID 2014384) has been included to identify a possible RDP DoS attack as described in KB2667402/CVE-2012-0152. I'm certain additional rules and detection logic are being added across the spectrum of detection options; check in with your vendor/provider accordingly.

Feel free to comment with methodology related to the above that works for you and thus may help others.

Russ McRee

@holisticinfosec

Keywords: denial of service DoS RDP Remote Code Execution Remote Desktop Protocol

4 comment(s)

INFOCON Yellow - Microsoft RDP - MS12-020

Published: 2012-03-16. Last Updated: 2012-03-16 15:35:54 UTC
by Swa Frantzen (Version: 1)

6 comment(s)

As we feared the MS12-020 bulletin from last black Tuesday caused a race for finding an exploit.
The last few evolutions in that process cause our worries to increase significantly. In order to help raise awareness and call administrators to action, we're raising our INFOCON to YELLOW for 24 hours.

Some history:

Luigi Auriemma found a problem on May 16th, 2011.
Microsoft was warned on August 24th, 2011 working with TippingPoint's Zero Day Initiative
Microsoft released bulletin MS12-020 on March 13th, 2012, crediting "Luigi Auriemma, working with TippingPoint's Zero Day Initiative, for reporting an issue described in MS12-020"
Luigi Auriemma released his work on March 16th, 2012

Luigi wrote today: "now that my proof-of-concept is out (yeah rdpclient.exe is the poc written by Microsoft in November 2011 using the example packet I sent to ZDI) I have decided to release my original advisory and proof-of-concept packet written the 16 May 2011... full-disclosure as usual :)" and he released his analysis and exploit of the vulnerability.

This is expected to speed up the efforts of the bad guys significantly and gives those having exposed RDP services very little time to fix before it will get exploited somehow.

The clock is ticking, please consider:

block off RDP from all sources but those you absolutely need
install the Microsoft patch

--
Swa Frantzen -- Section 66

Keywords: going yellow infocon infocon yellow yellow

6 comment(s)

VMware New and Updated Security Advisories

Published: 2012-03-16. Last Updated: 2012-03-16 11:17:17 UTC
by Guy Bruneau (Version: 1)

0 comment(s)

VMware issued the following security advisories:

VMware View privilege escalation and cross-site scripting (VMSA-2012-0004) [1] and VMware vCenter Server, Orchestrator, Update Manager, vShield, vSphere Client, ESXi and ESX address several security issues (VMSA-2012-0005) [2].

[1] http://www.vmware.com/security/advisories/VMSA-2012-0004.html
[2] http://www.vmware.com/security/advisories/VMSA-2012-0005.html

The following advisory has been updated:

VMware ESXi and ESX updates to third party library and ESX Service Console address several security issues (VMSA-2012-0001.1) [3]

[3] http://www.vmware.com/security/advisories/VMSA-2012-0001.html

-----------

Guy Bruneau IPSS Inc. gbruneau at isc dot sans dot edu

Keywords: ESX ESXi vCenter VMware vShield vSphere

0 comment(s)

ISC StormCast for Friday, March 16th 2012 http://isc.sans.edu/podcastdetail.html?id=2401