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Security Best Practice: Protect Yourself from DCE-RPC Big Endian Evasion Techniques

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Check Point Reference: SBP-2010-31
Date Published:
Severity:
Last Updated:
Source: IPS Research Center
Industry Reference(s): CVE-2010-0102
Protection Provided by: Security Gateway
  • R71
  • R70
Who is Vulnerable?
Computers and Networks
Vulnerability Description
DCE/RPC stands for "Distributed Computing Environment / Remote Procedure Calls". It is a Remote Procedure Call system that allows software to work across multiple computers, as if it were all working on the same computer. This system allows programmers to write distributed software without having to worry about the underlying network code.
Vulnerability Details
There are many known vulnerabilities in applications based on the DCE-RPC protocol. Though IDS and IPS devices have signatures to detect attacks exploiting these vulnerabilities, these devices can be evaded by using big endian notation. The DCE-RPC FLAGS field contains a bit that specifies the endianity of the data that follows. Attackers may use big endian notation as an IDS/IPS evasion technique.

Protection Overview
This protection will detect and block all DCE-RPC traffic in big endian notation.

In order for the protection to be activated, update your Security Gateway product to the latest IPS update. For information on how to update IPS, go to SBP-2006-05, Protection tab and select the version of your choice.

To configure the defense, select your product from the list below and follow the related protection steps.

Security Gateway: R70/R71

How Can I Protect My Network?
1. In the IPS tab, click Protections > By Protocol > Application Intelligence > MS-RPC.
2. In the right pane, double-click the following protection:

DCE-RPC Big Endian Evasion Technique

3. In the Protection Details window, click on Edit. Choose the protection's Action (Override IPS Policy with: Prevent/Detect), and apply Additional Settings. 
4. Install policy on all modules.

How Do I Know if My Network is Under Attack?
SmartView Tracker will log the following entries: 

Attack Name: DCE-RPC Enforcement Violation
Attack Information: DCE-RPC Big Endian evasion technique