An IIS 10.0 web server must maintain the confidentiality of controlled information during transmission through the use of an approved Transport Layer Security (TLS) version.

STIG ID: IIST-SV-000153  |  SRG: SRG-APP-000439-WSR-000156 | Severity: high |  CCI: CCI-002418

Vulnerability Discussion

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.

NIST SP 800-52 specifies the preferred configurations for government systems.

Check

Access the IIS 10.0 Web Server.

Navigate to:
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server

Verify a REG_DWORD value of "0" for "DisabledByDefault".
Verify a REG_DWORD value of "1" for "Enabled".

Navigate to:
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 2.0\Server
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server

Verify a REG_DWORD value of "1" for "DisabledByDefault".
Verify a REG_DWORD value of "0" for "Enabled".

If any of the respective registry paths do not exist or are configured with the wrong value, this is a finding.

Fix

Access the IIS 10.0 Web Server.

Navigate to:
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Server

Create a REG_DWORD named "DisabledByDefault" with a value of "0".
Create a REG_DWORD named "Enabled" with a value of "1".

Navigate to:
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.0\Server
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.1\Server
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 2.0\Server
HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\SSL 3.0\Server

For each protocol:
Create a REG_DWORD named "DisabledByDefault" with a value of "1".
Create a REG_DWORD named "Enabled" with a value of "0".
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