A private web server must utilize an approved TLS version.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-2262	WG340 IIS6	SV-28468r2_rule	ECSC-1	Medium

Description

Transport Layer Security (TLS) encryption is a required security setting for a private web server. Encryption of private information is essential to ensuring data confidentiality. If private information is not encrypted, it can be intercepted and easily read by an unauthorized party. A private web server must use a FIPS 140-2 approved TLS version, and all non-FIPS-approved SSL versions must be disabled. FIPS 140-2 approved TLS versions include TLS V1.0 or greater. NIST SP 800-52 specifies the preferred configurations for government systems.

STIG	Date
IIS6 Site	2015-06-01

Details

Check Text ( C-37443r3_chk )

1. Open the IIS Manager > Right click on the web site to be examined > Select properties > Select the Web Site tab > Note the entry for the SSL port (i.e. 443). 2. Select the Directory Security tab > Select the Edit button in the Secure communications section. 3. Ensure the Require secure channel (SSL) and Require 128-bit encryption checkboxes are checked. If the Require secure channel (SSL) and Require 128-bit encryption checkboxes are not checked, this is a finding. If the site requires SSL and 128-bit encryption, then the version of SSL/TLS also needs to be verified. The following registry keys need to exist and be set to not allow anything lower than TLS. This can be accomplished by ensuring the following value exists in each of the keys: Enabled REG_DWORD 0 HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\PCT 1.0\Client HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\PCT 1.0\Server HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 2.0\Client HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 2.0\Server HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 3.0\Client HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 3.0\Server If these keys are not set to a DWORD value of 0, this is a finding. If the keys do not contain the value "Enabled", this would also be a finding. The keys for TLS 1.0 do not require the Enabled value to be present, but if it is, it needs to be set to REG_DWORD 1, to enable TLS. If the "Enabled" value is present and set to 0, this is a finding. NOTE: In some cases the web servers are configured in an environment to support load balancing. This configuration most likely utilizes a content switch to control traffic to the various web servers. In this situation, the SSL certificate for the web sites may be installed on the content switch vs. the individual web sites. This solution is acceptable as long as the web servers are isolated from the general population LAN. We do not want users to have the ability to bypass the content switch to access the web sites.

Fix Text (F-32689r3_fix)

1. Obtain and install a server certificate from a .mil Certificate Authority or approved DoD ECA. 2. Open the IIS Manager > right click on the website to be examined > select properties > select the Directory Security tab > select the Edit button in the Secure communications section. 3. Select Require secure channel (SSL) and Require 128-bit encryption check boxes. 4. Set the version of SSL/TLS by creating and setting the following registry to not allow anything lower than TLS. Ensure the following value exists in each of the keys: Enabled REG_DWORD 0 HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\PCT 1.0\Client HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\PCT 1.0\Server HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 2.0\Client HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 2.0\Server HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 3.0\Client HKey_Local_Machine\System\CurrentControlSet\Control\SecurityProviders \SCHANNEL\Protocols\SSL 3.0\Server The keys for TLS 1.0 do not require the Enabled value to be present, but if it is, it needs to be set to REG_DWORD 1, to enable TLS.