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HistoryMay 09, 2006 - 12:00 a.m.

SYMSA-2006-003: Cisco Secure ACS for Windows - Administrator Password Disclosure

2006-05-0900:00:00
vulners.com
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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 : http://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"

    http://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"

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

    "How to Manage Remote Access to the Registry"

    http://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 (http://cve.mitre.org), which standardizes
names for security problems.

    CVE-2006-0561
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Copyright (c) 2006 by Symantec Corp.
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