I created a custom vulnerability signature that helps to detect and block the recently discovered Joomla RCE zero day which has since been patched by the vendor. I've opened a case with an engineer and he suggesed some additional protections until an official signature is released. The engineer suggested I post it here so that other people may benefit.
It checks for the following http headers in a GET request:
I don't see an option to upload the .xml so here is the full xml code, sorry for the length:
<vulnerability-threat version="6.1.0"> <entry name="41001"> <signature> <standard> <entry name="Suspicious HTTP Header"> <and-condition> <entry name="And Condition 1"> <or-condition> <entry name="Or Condition 1"> <operator> <pattern-match> <qualifier> <entry name="http-method"> <value>GET</value> </entry> </qualifier> <pattern>((JDatabaseDriverMysqli)|(JSimplepieFactory)|(disconnectHandlers))</pattern> <context>http-req-headers</context> </pattern-match> </operator> </entry> <entry name="Or Condition 2"> <operator> <pattern-match> <qualifier> <entry name="http-method"> <value>GET</value> </entry> </qualifier> <pattern>eval(base64_decode($_POST))</pattern> <context>http-req-headers</context> </pattern-match> </operator> </entry> </or-condition> </entry> </and-condition> <order-free>no</order-free> <scope>protocol-data-unit</scope> <comment>User agent strings identified in the reference link</comment> </entry> </standard> </signature> <default-action> <drop-packets/> </default-action> <cve> <member>CVE-2015-8562</member> </cve> <reference> <member>https://wp.me/p3AjUX-u58</member> </reference> <vendor> <member>Joomla</member> </vendor> <threatname>Joomla CVE-2015-8562</threatname> <severity>critical</severity> <direction>client2server</direction> <comment>Remote Code Execution Vulnerability. This signature is only a band-aid per the link in the reference below.</comment> <affected-host> <server>yes</server> </affected-host> </entry> </vulnerability-threat>
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