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Background of the issue

By default, a "High" security level is selected during OfficeScan server installation. However, the installation allows the administrator to change this setting to "Normal" instead.

When OfficeScan is installed with "Normal" security level, it grants the user "Everyone" with a "Full Control" to the OfficeScan client program directory and files. It also allows OfficeScan client services to run under SYSTEM.

An attacker with unprivileged access to an affected system can overwrite any of these service executables with malicious executable content and run with the privileges of SYSTEM.

 
Trend Micro is aware of a re-tweet from Tavis Ormandy regarding some potential ACL issues with OfficeScan. Although we have not received any formal vulnerability claims on this issue, we have done some investigation and believe that the user may have altered or changed the default (and recommended) OfficeScan Agent Security Setting from “High”, which restricts users from accessing OfficeScan agent files and registry entries. We are considering a future update that may remove the option to change this security setting via UI completely in light of this.

OfficeScan 11.0

To remove this potential vulnerability, customers who changed the default "High" setting to "Normal" should change this setting back to "High".

  1. Install OfficeScan 11.0 Service Pack 1 Critical Patch 4150.
  2. Log in to the OfficeScan server console.
  3. Go to Agents > Agent Management.
  4. Select the Domain or Agent.
  5. Click Settings and go to Privileges and Other Settings.
  6. Click Other Settings tab and look for the OfficeScan Agent Security Settings section.
  7. From the Access Permissions options, choose High.
     
    With a "High" Security Setting, the OfficeScan agent installation directory inherits the rights of the Program Files folder, and the OfficeScan agent’s registry entries inherit permissions from the HKLM\Software key. For most Active Directory configurations, this automatically limits the "normal" users (those without administrator privileges) to read-only access.
  8. If you have selected domain(s) or agent(s) in the agent tree, click Save. If you have clicked the root domain icon, choose from the following options:
    • Apply to All Agents: Applies settings to all existing agents and to any new agent added to an existing/future domain - Future domains are domains not yet created at the time you configured the settings.
    • Apply to Future Domains Only: Applies settings only to agents added to future domains - This option will not apply settings to new agents added to an existing domain.

OfficeScan XG

This solution is for a scenario where OSCE XG removes the Officescan Agent Security Settings option and sets the default to "High" during installation.

To verify the Security Level:

  1. Open ofcscan.ini under ...\Trend Micro\OfficeScan Client\.
  2. Check the value of the Client_Security parameter under [INI_CLIENT_SECTION]. "0" is Normal and "1" is High.

If you changed the default "High" setting to "Normal", change the setting back to "High" to remove this potential vulnerability:

  1. Open ofcscan.ini as Administrator under ...\Trend Micro\OfficeScan\PCCSRV.
  2. Change the value of the Client_Security parameter under [INI_CLIENT_SECTION] from "0" to "1".
  3. Log into the OSCE server console.
  4. Go to Agents > Agent Management.
  5. Right-click the root domain icon.
  6. Click Settings > Privileges and Other Settings > Apply to All Agents.
  7. Perform a manual update on the machine.
Keywords: local privilege escalation vulnerability,normal security level,officescan client folder permissions,critical patch-4150-r1,osce-11-sp1-win-en-criticalpatch-4150-r1.exe