Monitoring network connections

<?xml version='1.0' encoding='UTF-8'?>

<rule>

  <description>

    <name>External Network Connection from rundll32.exe with Unpopular Parent [A0504b]</name>

    <category>Communication</category>

    <os>Windows</os>

    <severity>48</severity>

    <mitreattackid>T1218.011</mitreattackid>

    <explanation>Rundll32 is a Microsoft Windows system utility that provides an entry point and minimal framework for executing dynamic load libraries. The rule monitors network connections to public range IP addresses from Rundll32 that was started from an unpopular process.</explanation>

    <benignCauses>This usually happens when benign less popular software prints on the network printer.</benignCauses>

    <maliciousCauses>Often used by script malware for downloading or reporting</maliciousCauses>

    <recommendedActions>1. Evaluate the parent process, its command line and execution chain.

2. Evaluate the target IP, check events for creating, modifying and executing files by the script interpreter. 

3. If a suspicious activity is detected, start the incident response process (for example, disconnect the computer from the internet, update your antivirus product and scan the computer for malware, send samples for analysis, block module, etc.).</recommendedActions>

  </description>

  <definition>

    <parentprocess>

      <operator type="AND">

        <condition component="LiveGrid" property="Popularity" condition="less" value="1000"/>

        <operator type="NOT">

          <operator type="OR">

            <condition component="Module" property="SignatureType" condition="is" value="Trusted"/>

            <condition component="Enterprise" property="Safe" condition="is" value="1"/>

          </operator>

        </operator>

      </operator>

    </parentprocess>

    <process>

      <operator type="OR">

        <condition component="FileItem" property="FileName" condition="is" value="rundll32.exe"/>

        <condition component="Module" property="OriginalFileName" condition="is" value="RUNDLL32.exe"/>

      </operator>

    </process>

    <operations>

      <operation type="TcpIpConnect">

        <operator type="OR">

          <operator type="NOT">

            <operator type="OR">

              <condition component="Network" property="IpAddressV4" condition="is" value="10.0.0.0/8"/>

              <condition component="Network" property="IpAddressV4" condition="is" value="172.16.0.0/12"/>

              <condition component="Network" property="IpAddressV4" condition="is" value="192.168.0.0/16"/>

              <condition component="Network" property="IpAddressV4" condition="is" value="127.0.0.0/8"/>

            </operator>

          </operator>

          <operator type="NOT">

            <operator type="OR">

              <condition component="Network" property="IpAddressV6" condition="is" value="fc00::/7"/>

              <condition component="Network" property="IpAddressV6" condition="is" value="::1/128"/>

            </operator>

          </operator>

        </operator>

      </operation>

    </operations>

  </definition>

  <maliciousTarget name="current"/>

  <actions>

    <action name="TriggerDetection"/>

    <action name="StoreEvent"/>

  </actions>

</rule>