5.9 Ensure Old HTTP Protocol Versions Are Disallowed
Profile Applicability
Level 1
Description
The Apache modules mod_rewrite or mod_security can be used to disallow old and invalid HTTP protocols versions. The HTTP version 1.1 RFC is dated June 1999 and has been supported by Apache since version 1.2. It should no longer be necessary to allow ancient versions of HTTP such as 1.0 and prior.
Rationale
Many malicious automated programs, vulnerability scanners and fingerprinting tools will send abnormal HTTP protocol versions to see how the web server responds. These requests are usually part of the attacker's enumeration process and therefore it is important that we respond by denying these requests.
Audit
Perform the following to determine if the recommended state is implemented:
Locate the Apache configuration files and included configuration files.
Verify there is a rewrite condition within the global server context that disallows requests that do not include the HTTP/1.1 as shown below.
Verify the following directives are included in each section so that the main server settings will be inherited.
RewriteEngine On
RewriteOptions Inherit
Remediation
Perform the following to implement the recommended state:
Load the mod_rewrite module for Apache by doing either one of the following:
Build Apache with mod_rewrite statically loaded during the build, by adding the --enable-rewrite option to the ./configure script.
./configure --enable-rewrite.
Or, dynamically loading the module with the LoadModule directive in the httpd.conf configuration file.
LoadModule rewrite_module modules/mod_rewrite.so
Set the apache2 profile to enforce mode, reload AppArmor, and then test the web site functionality again.
# aa-enforce /usr/sbin/apache2
# /etc/init.d/apparmor reload
Default Value
The default Apache profile is very permissive.
References
No external references provided in the PDF for this control.
CIS Controls
Controls Version
Control
IG 1
IG 2
IG 3
v8
2.5 Allowlist Authorized SoftwareUse technical controls, such as application allowlisting, to ensure that only authorized software can execute or be accessed. Reassess bi-annually, or more frequently.
●
●
v7
2.7 Utilize Application WhitelistingUtilize application whitelisting technology on all assets to ensure that only authorized software executes and all unauthorized software is blocked from executing on assets.
●
Profile
Level 1 | Automated
1---2name: cis-apache24-5-93description: Ensure Old HTTP Protocol Versions Are Disallowed4---56# 5.9 Ensure Old HTTP Protocol Versions Are Disallowed78## Profile Applicability910- Level 11112## Description1314The Apache modules `mod_rewrite` or `mod_security` can be used to disallow old and invalid HTTP protocols versions. The HTTP version 1.1 RFC is dated June 1999 and has been supported by Apache since version 1.2. It should no longer be necessary to allow ancient versions of HTTP such as 1.0 and prior.1516## Rationale1718Many malicious automated programs, vulnerability scanners and fingerprinting tools will send abnormal HTTP protocol versions to see how the web server responds. These requests are usually part of the attacker's enumeration process and therefore it is important that we respond by denying these requests.1920## Audit2122Perform the following to determine if the recommended state is implemented:23241. Locate the Apache configuration files and included configuration files.252. Verify there is a rewrite condition within the global server context that disallows requests that do not include the HTTP/1.1 as shown below.263. `RewriteEngine On`274. `RewriteCond %{THE_REQUEST} !(HTTP/1\.1|HTTP/2\.0)$`285. `RewriteRule .* - [F]`296. Verify the following directives are included in each section so that the main server settings will be inherited.307. `RewriteEngine On`318. `RewriteOptions Inherit`3233## Remediation3435Perform the following to implement the recommended state:36371. Load the `mod_rewrite` module for Apache by doing either one of the following:38 - Build Apache with `mod_rewrite` statically loaded during the build, by adding the `--enable-rewrite` option to the `./configure` script.39 - `./configure --enable-rewrite.`40 - Or, dynamically loading the module with the `LoadModule` directive in the `httpd.conf` configuration file.41 - `LoadModule rewrite_module modules/mod_rewrite.so`422. Set the apache2 profile to enforce mode, reload AppArmor, and then test the web site functionality again.433. `# aa-enforce /usr/sbin/apache2`444. `# /etc/init.d/apparmor reload`4546## Default Value4748The default Apache profile is very permissive.4950## References5152No external references provided in the PDF for this control.5354## CIS Controls5556| Controls Version | Control | IG 1 | IG 2 | IG 3 |57| ---------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---- | ---- | ---- |58| v8 | 2.5 Allowlist Authorized Software<br>Use technical controls, such as application allowlisting, to ensure that only authorized software can execute or be accessed. Reassess bi-annually, or more frequently. | | ● | ● |59| v7 | 2.7 Utilize Application Whitelisting<br>Utilize application whitelisting technology on all assets to ensure that only authorized software executes and all unauthorized software is blocked from executing on assets. | | | ● |6061## Profile6263- Level 1 | Automated
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