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                    Symantec Vulnerability Research                                   
                    https://www.symantec.com/research
                          Security Advisory

Advisory ID   : SYMSA-2006-003
Advisory Title: Cisco Secure ACS for Windows - Administrator 
                Password Disclosure
Author        : Andreas Junestam
Release Date  : 05-08-2006
Application   : Cisco Secure ACS 3.x for Windows
Platform      : Microsoft Windows
Severity      : System access / exploit available 
Vendor status : Vendor verified, workaround available
CVE Number    : CVE-2006-0561
Reference     : https://www.securityfocus.com/bid/16743


Overview: 

  Cisco Secure ACS is a central administration platform for 
  Cisco network devices. It controls authentication and 
  authorization for enrolled devices. Administrative 
  passwords for locally-defined users are stored in such a 
  way they can be obtained from the Windows registry. If 
  remote registry access is enabled, this can be done over 
  the network.

  If Cisco Secure ACS is configured to use an external 
  authentication service such as Windows Active Directory or
  LDAP, the passwords for users stored by those services are
  not vulnerable to this issue.


Details: 

  Cisco Secure ACS 3.x for Windows stores passwords for 
  administrative users in the registry. The passwords are 
  encrypted using the Crypto API Microsoft Base Cryptographic 
  Provider v1.0. Along with the passwords, ACS also stores 
  the key used to encrypt the information. This information 
  can easily be obtained locally by a Windows administrator, 
  and if remote registry access is enabled, it can be 
  obtained over the network. With this, the clear-text 
  passwords can be recovered by decrypting the information 
  in the registry with the supplied key. Access to these 
  passwords provides access to all Cisco devices controlled 
  by the ACS server.


Vendor Response:


  Cisco Secure ACS 3.x for Windows stores the passwords of 
  ACS administrators in the Windows registry in an encrypted 
  format. A locally generated master key is used to 
  encrypt/decrypt the ACS administrator passwords. The master
  key is also stored in the Windows registry in an encrypted 
  format. Using Microsoft cryptographic routines, it is 
  possible for a user with administrative privileges to a 
  system running Cisco Secure ACS to obtain the clear-text 
  version of the master key. With the master key, the user 
  can decrypt and obtain the clear-text passwords for all 
  ACS administrators. With administrative credentials to 
  Cisco Secure ACS, it is possible to change the password 
  for any locally defined users. This may be used to gain 
  access to network devices configured to use Cisco Secure 
  ACS for authentication.

  If remote registry access is enabled on a system running 
  Cisco Secure ACS, it is possible for a user with
  administrative privileges (typically domain administrators) 
  to exploit this vulnerability.

  If Cisco Secure ACS is configured to use an external 
  authentication service such as Windows Active Directory / 
  Domains or LDAP, the passwords for users stored by those 
  services are not at risk to compromise via this 
  vulnerability.

  This vulnerability only affects version 3.x of Cisco Secure 
  ACS for Windows. Cisco Secure ACS for Windows 4.0.1 and Cisco 
  Secure ACS for UNIX are not vulnerable. Cisco Secure ACS 3.x 
  appliances do not permit local or remote Windows registry 
  access and are not vulnerable.
     
Workaround:

  It is possible to mitigate this vulnerability by 
  restricting access to the registry key containing the 
  ACS administrators' passwords. One feature of Windows 
  operating systems is the ability to modify the permissions 
  of a registry key to remove access even for local or 
  domain administrators. Using this feature, the registry 
  key containing the ACS administrators' passwords can be 
  restricted to only the Windows users with a need to 
  maintain the ACS installation or operate the ACS services.

  The following registry key and all of its sub-keys need to 
  be protected.

HKEY_LOCAL_MACHINE\SOFTWARE\Cisco\CiscoAAAv3.3\CSAdmin\Administrators

  Note: The "CiscoAAAv3.3" portion of the registry key path
  may differ slightly depending on the version of Cisco Secure
  ACS for Windows that is installed.

  There are two general deployment scenarios for Cisco Secure
  ACS. The Windows users that need permissions to the registry
  key will depend on the deployment type.

  * If Cisco Secure ACS is not installed on a Windows domain 
  controller, access to the registry key should be limited to
  only the local Windows SYSTEM account and specific local / 
  domain administrators who will be performing software 
  maintenance on the ACS installation. 
  
  * If Cisco Secure ACS is installed on a Windows domain 
  controller, access to the registry key should be limited to 
  the domain account which ACS is configured to use for its 
  services, the local Windows SYSTEM account and specific 
  local / domain administrators who will be performing 
  software maintenance on the ACS installation.

  For information about editing the Windows registry, please 
  consult the following Microsoft documentation.

  "Description of the Microsoft Windows registry"

  https://support.microsoft.com/default.aspx?scid=kb;EN-US;256986

  Further mitigation against remote exploitation can be 
  achieved by restricting access to authorized users or 
  disabling remote access to the Windows registry on systems
  running Cisco Secure ACS for Windows. For information on
  restricting remote registry access, please consult the
  following Microsoft documentation.

  "How to restrict access to the registry from a remote computer"

  https://support.microsoft.com/kb/q153183

  "How to Manage Remote Access to the Registry"

  https://support.microsoft.com/kb/q314837
  
Recommendation:
  
  Follow your organization's testing procedures before 
  applying patches or workarounds.  See Cisco's instructions
  on how to place an ACL on the Registry Key, and also how 
  to restrict remote access to the Windows registry.

  These recommendations do not eliminate the vulnerability, 
  but provide some mitigation.


Common Vulnerabilities and Exposures (CVE) Information:

The Common Vulnerabilities and Exposures (CVE) project has assigned 
the following names to these issues.  These are candidates for 
inclusion in the CVE list (https://cve.mitre.org), which standardizes 
names for security problems.


  CVE-2006-0561

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