V-225234
SV-225234r1188289_rule
CAT III
.NET default proxy settings must be reviewed and approved.
From: Microsoft DotNet Framework 4.0 Security Technical Implementation Guide (V2R8)
Description
<VulnDiscussion>The .Net framework can be configured to utilize a different proxy or altogether bypass the default proxy settings in the client's browser. This may lead to the framework using a proxy that is not approved for use. If the proxy is malicious, this could lead to a loss of application integrity and confidentiality.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
Check Procedure
Open Windows explorer and search for all "*.exe.config" and "machine.config" files.
The referenced file is in the WinSxS directory (original source component file used when the Windows component was installed).
If the files under WinSxS are read-only and cannot be modified, this is not a finding.
Search each file for the "defaultProxy" element.
<defaultProxy
enabled="true|false"
useDefaultCredentials="true|false"
<bypasslist> … </bypasslist>
<proxy> … </proxy>
<module> … </module>
/>
If the "defaultProxy" setting "enabled=false" or if the "bypasslist", "module", or "proxy" child elements have configuration entries and there are no documented approvals from the authorizing official (AO), this is a finding.
If the "defaultProxy" element is empty or if "useSystemDefault =True” then the framework is using default browser settings, this is not a finding.
Fix Text
Open Windows explorer and search for all "*.exe.config" and "machine.config" files.
Search each file for the "defaultProxy" element.
Clear the values contained in the "defaultProxy" element, and the "bypasslist", "module", and "proxy" child elements.
The IAO must provide documented approvals of any non-default proxy servers.
CCI Reference
CCI-000366- Created
- 2026-01-14 17:55:45
- Last Updated
- 2026-04-07 20:08:23