Hardening IIS

Revision as of 15:53, 12 July 2018 by Bill Sempf (talk | contribs) (Formatted the layout of the headers.)

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Draft - Work In Progress

Basic configuration

Disable directoryBrowsing

Avoid wildcard host headers

Ensure applicationPoolIdentity is configured for all application pools

Use an unique applicationPool per site

Disable IIS detailed error page from displaying remotely

Request filtering

Configure maxAllowedContentLength

Configure maxURL request filter

Configure MaxQueryString request filter

Reject non-ASCII characters in URLs

Reject double-encoded requests

Disable HTTP trace requests

Disallow unlisted file extensions

Enable Dynamic IP Address Restrictions

Transport Encryption

SSL/TLS settings are controlled at the SChannel level. They are set machine wide and IIS respects these values.

A list of recommendations for IIS

Disable SSL v2/v3
Disable TLS 1.0
Disable TLS 1.1
Ensure TLS 1.2 is enabled
Disable weak cipher suites (NULL cipher suites, DES cipher suites, RC4 cipher suites, Triple DES, etc)
Ensure TLS cipher suites are correctly ordered


HSTS support

IIS recently (Windows Server 1709) added turnkey support for HSTS


CORS support

If you choose not to handle CORS in your application, we ship an IIS an IIS module to help configure CORS



Sourabh Shirhatti (Microsoft)

Bill Sempf (bill.sempf@owasp.org)