From 752b2ad7b1a2ecaa60f0988f4272663e7c7bcf38 Mon Sep 17 00:00:00 2001
From: Alexander Stein <61464190+ohsh6o@users.noreply.github.com>
Date: Mon, 7 Dec 2020 12:50:13 -0500
Subject: [PATCH] Check for Additional Extraneous Implemented Requirements for
 Controls (#34)

* Fix analysis report looping bug.

Since we were looping through items that are > 1, we were starting to
loop through the 2nd item of a list of reports (//reports/report) in a
analysis template in a variable. Noticed this when looking at result of
a lv:report() on implemented-requirements.

* Woops, misread docs syntax.

* Fix-up actual assertion.

* Add tests.

* Fix spacing issue.

* And fix misleading comment for negative test.
---
 resources/validations/src/ssp.sch    |  6 ++--
 resources/validations/test/ssp.xspec | 44 ++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/resources/validations/src/ssp.sch b/resources/validations/src/ssp.sch
index ddd339387..bb2e6de7c 100644
--- a/resources/validations/src/ssp.sch
+++ b/resources/validations/src/ssp.sch
@@ -179,9 +179,9 @@
             <xsl:otherwise> items total. </xsl:otherwise>
         </xsl:choose>
         <xsl:for-each select="$analysis/reports/report">
-            <xsl:if test="position() gt 1 and not(position() eq last())">
+            <xsl:if test="position() gt 0 and not(position() eq last())">
                 <xsl:value-of select="current()/@count"/> set as <xsl:value-of select="current()/@value"/>, </xsl:if>
-            <xsl:if test="position() gt 1 and position() eq last()"
+            <xsl:if test="position() gt 0 and position() eq last()"
                 > and <xsl:value-of select="current()/@count"/> set as <xsl:value-of select="current()/@value"/>.</xsl:if>
             <xsl:sequence select="."/>
         </xsl:for-each>
@@ -217,8 +217,10 @@
         <sch:let name="required-controls" value="$selected-profile/*//o:control"/>
         <sch:let name="implemented" value="o:implemented-requirement"/>
         <sch:let name="missing" value="$required-controls[not(@id = $implemented/@control-id)]"/>
+        <sch:let name="extraneous" value="$implemented[not(@control-id = $required-controls/@id)]"/>
         <sch:report id="each-required-control-report" test="count($required-controls) > 0">The following <sch:value-of select="count($required-controls)"/><sch:value-of select="if (count($required-controls)=1) then ' control' else ' controls'"/> are required: <sch:value-of select="$required-controls/@id"/></sch:report>
         <sch:assert id="incomplete-implementation-requirements" test="not(exists($missing))">This SSP has not implemented <sch:value-of select="count($missing)"/><sch:value-of select="if (count($missing)=1) then ' control' else ' controls'"/>: <sch:value-of select="$missing/@id"/></sch:assert>
+        <sch:assert id="extraneous-implemented-requirements" test="not(exists($extraneous))">This SSP has implemented <sch:value-of select="count($extraneous)"/> extraneous<sch:value-of select="if (count($extraneous)=1) then ' control' else ' controls'"/> not needed given the selected profile: <sch:value-of select="$extraneous/@control-id"/></sch:assert>
         <sch:let name="results" value="$ok-values => lv:analyze(//o:implemented-requirement/o:annotation[@name='implementation-status'])"/>
         <sch:let name="total" value="$results/reports/@count"/>
         <sch:report id="control-implemented-requirements-stats" test="count($results/errors/error) = 0"><sch:value-of select="$results => lv:report() => normalize-space()"/></sch:report>
diff --git a/resources/validations/test/ssp.xspec b/resources/validations/test/ssp.xspec
index fdb7bdd34..ce23b670c 100644
--- a/resources/validations/test/ssp.xspec
+++ b/resources/validations/test/ssp.xspec
@@ -111,6 +111,50 @@
                 <x:expect-assert id="incomplete-implementation-requirements" label="it is invalid."/>
             </x:scenario>
         </x:scenario>
+        <x:scenario label="when an extraneous control not required by the profile is implemented">
+            <x:context>
+                <system-security-plan xmlns="http://csrc.nist.gov/ns/oscal/1.0">
+                    <system-characteristics>
+                        <!--
+                            NOTE: At this time, 800-53 control AC-5 is not required
+                            for the FedRAMP LOW profile. It is required for the FedRAMP
+                            HIGH profile, so this is extraneous.
+                        -->
+                        <security-sensitivity-level>low</security-sensitivity-level>
+                    </system-characteristics>
+                    <control-implementation>
+                        <implemented-requirement control-id="ac-5" uuid="373c8a10-7885-4209-9e55-0b69747cb6b9">
+                            <annotation name="implementation-status" ns="https://fedramp.gov/ns/oscal" value="implemented">
+                            <remarks></remarks>
+                            </annotation>
+                        </implemented-requirement>
+                    </control-implementation>
+                </system-security-plan>
+            </x:context>
+            <x:expect-assert id="extraneous-implemented-requirements" label="it is invalid."/>
+        </x:scenario>
+        <x:scenario label="when no extraneous control is implemented except those required by the profile">
+            <x:context>
+                <system-security-plan xmlns="http://csrc.nist.gov/ns/oscal/1.0">
+                    <system-characteristics>
+                        <!--
+                            NOTE: At this time, 800-53 control AC-1 is required for
+                            the FedRAMP LOW profile. It is required for the FedRAMP
+                            HIGH profile, so this is extraneous.
+                        -->
+                        <security-sensitivity-level>low</security-sensitivity-level>
+                    </system-characteristics>
+                    <control-implementation>
+                        <implemented-requirement control-id="ac-1" uuid="4b81d5aa-2149-4b7b-ab28-69e390226784">
+                            <annotation name="implementation-status" ns="https://fedramp.gov/ns/oscal" value="partial">
+                            <remarks></remarks>
+                            </annotation>
+                        </implemented-requirement>
+                    </control-implementation>
+                </system-security-plan>
+            </x:context>
+            <x:expect-not-assert id="extraneous-implemented-requirements" label="it is valid."/>
+        </x:scenario>
     </x:scenario>
     <x:scenario label="For FedRAMP Automation helper functions">
         <x:scenario label="with if-empty-default">