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Security Best Practice: Protect Yourself from Microsoft SMB Invalid Write Mode Evasion Techniques

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Check Point Reference: SBP-2010-32
Date Published:
Severity:
Last Updated:
Source: IPS Research Center
Industry Reference(s): CVE-2010-0102
Protection Provided by: Security Gateway
  • R71
  • R70
VPN-1
  • NGX R65
VSX
  • NGX R65
Who is Vulnerable?
Microsoft Windows users
Vulnerability Description
The SMB Protocol is a network file sharing protocol that is implemented in Microsoft Windows.
There are many known vulnerabilities in applications based on the SMB protocol. Though IDS and IPS devices have signatures to detect attacks exploiting these vulnerabilities, these devices can be evaded. 
Vulnerability Details
SMB requests with invalid flags are usually discarded by the receiving host. Correct reassembly of SMB conversations requires that the inspection device discards the same payload as the receiving server. Attackers may use SMB write requests containing an invalid Write Mode and random payload as an IDS/IPS evasion technique.

Protection Overview
This protection will detect and block non-compliant SMB write requests.

In order for the protection to be activated, update your Security Gateway/VPN-1 product to the latest IPS/SmartDefense update. For information on how to update IPS/SmartDefense,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 > Microsoft Networks.
2. In the right pane, double-click the following protection:

Microsoft SMB Invalid Write Mode 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: Windows SMB Protection Violation
Attack Information: Microsoft SMB invalid write mode evasion technique

VPN-1 NGX R65 & VSX NGX R65

How Can I Protect My Network?
1. In the SmartDefense tab, click Application Intelligence > MS-RPC.
2. Select the following protection:

Microsoft SMB Invalid Write Mode Evasion Technique

3. In the configuration pane, under Settings > Mode, check Active.
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: Windows SMB Protection Violation
Attack Information: Microsoft SMB invalid write mode evasion technique