Title

Internet Explorer Processes for MIME handling is not enabled. Explorer (Cat II impact)

Discussion

Internet Explorer uses Multipurpose Internet Mail Extensions (MIME) data to determine file handling procedures for files received through a Web server. The Consistent MIME Handling\Internet Explorer Processes policy setting determines whether Internet Explorer requires that all file-type information provided by Web servers be consistent. For example, if the MIME type of a file is text/plain but the MIME data indicates that the file is really an executable file, Internet Explorer changes its extension to reflect this executable status. This capability helps ensure that executable code cannot masquerade as other types of data that may be trusted. If you enable this policy setting, Internet Explorer examines all received files and enforces consistent MIME data for them. If you disable or do not configure this policy setting, Internet Explorer does not require consistent MIME data for all received files and will use the MIME data provided by the file. MIME file-type spoofing is a potential threat to your organization. Ensuring that these files are consistent and properly labeled helps prevent malicious file downloads from infecting your network. Therefore, this appendix recommends you configure this policy as Enabled for all environments specified in this guide.

Check Content

The policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Internet Explorer -> Security Features -> Consistent Mime Handling -> "Internet Explorer Processes" will be set to “Enabled”. Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_MIME_HANDLING Criteria: If the value explorer.exe is REG_SZ = 1, this is not a finding.

Fix Text

The policy value for Computer Configuration -> Administrative Templates -> Windows Components -> Internet Explorer -> Security Features -> Consistent Mime Handling -> "Internet Explorer Processes" will be set to “Enabled”. Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_MIME_HANDLING Criteria: Set the value explorer.exe to REG_SZ = 1.

Additional Identifiers

Rule ID: SV-16412r1_rule

Vulnerability ID: V-15565

Group Title:

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.