CCE-33792-3Platform: cpe:/o:microsoft:windows_8.1 | Date: (C)2015-10-14 (M)2023-07-04 |
MSS: (NoDefaultExempt) Configure IPSec exemptions for various types of network traffic.
The registry value entry NoDefaultExempt was added to the template file in the HKEY_LOCAL_MACHINESystemCurrentControlSetServicesIPSEC registry key. The entry appears as MSS: (NoDefaultExempt) Configure IPSec exemptions for various types of network traffic in the SCE.
The default exemptions to IPsec policy filters are documented in the online help for the specific operating system. These filters make it possible for Internet Key Exchange (IKE) and the Kerberos authentication protocol to function. The filters also make it possible for the network Quality of Service (QoS) to be signaled (RSVP) when the data traffic is secured by IPsec, and for traffic that IPsec might not secure such as multicast and broadcast traffic.
IPsec is increasingly used for basic host-firewall packet filtering, particularly in Internet-exposed scenarios, and the affect of these default exemptions has not been fully understood. Therefore, some IPsec administrators may create IPsec policies that they think are secure, but are not actually secure against inbound attacks that use the default exemptions.
For additional information, see the Knowledge Base article 811832, 'IPSec Default Exemptions Can Be Used to Bypass IPsec Protection in Some Scenarios.'
Parameter:
[allow all exemption (least secure)/multicast, broadcast and ISAKMP exempt (best for windows xp)/rsvp, broadcast and isakmp are exempt/only isakmp is exempt (recommended for windows server 2003)]
Technical Mechanism:
(1) GPO: Computer ConfigurationWindows SettingsSecurity SettingsLocal PoliciesSecurity Options!MSS: (NoDefaultExempt) Configure IPSec exemptions for various types of network traffic.
(2) REG: HKEY_LOCAL_MACHINESystemCurrentControlSetServicesIPSEC!NoDefaultExempt
CCSS Severity: | CCSS Metrics: |
CCSS Score : 8.1 | Attack Vector: NETWORK |
Exploit Score: 2.2 | Attack Complexity: HIGH |
Impact Score: 5.9 | Privileges Required: NONE |
Severity: HIGH | User Interaction: NONE |
Vector: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | Scope: UNCHANGED |
| Confidentiality: HIGH |
| Integrity: HIGH |
| Availability: HIGH |
| |
References: Resource Id | Reference |
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SCAP Repo OVAL Definition | oval:org.secpod.oval:def:22377 |