QRadar Community Edition 7.3.1.6 Arbitrary Object Instantiation

2020-04-21T00:00:00
ID PACKETSTORM:157337
Type packetstorm
Reporter Yorick Koster
Modified 2020-04-21T00:00:00

Description

                                        
                                            `------------------------------------------------------------------------  
Arbitrary class instantiation & local file inclusion vulnerability in  
QRadar Forensics web application  
------------------------------------------------------------------------  
Yorick Koster, September 2019  
  
------------------------------------------------------------------------  
Abstract  
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It was found that the QRadar Forensics web application is vulnerable to  
instantiation of arbitrary objects based on user-supplied input. An  
authenticated attacker can abuse this to perform various types of  
attacks including Server-Side Request Forgery and (potentially)  
arbitrary execution of code.  
  
In addition, the same input is also used to include PHP files, which can  
be used to include arbitrary local files. By abusing the case upload  
functionality, it is possible for an authenticated user to upload a PHP  
file to a known location on the system. By exploiting the local file  
inclusion vulnerability it is possible to run arbitrary PHP code. This  
code will be executed with the privileges of the Apache system user  
(generally the nobody user).  
  
------------------------------------------------------------------------  
See also  
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CVE-2020-4272 [2]  
6189645 [3] - IBM QRadar SIEM is vulnerable to instantiation of  
arbitrary objects (CVE-2020-4272)  
  
------------------------------------------------------------------------  
Tested versions  
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This issue was successfully verified on QRadar Community Edition [4]  
version 7.3.1.6 (7.3.1 Build 20180723171558).  
  
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Fix  
------------------------------------------------------------------------  
IBM has released the following versions of QRader in which this issue  
has been resolved:  
  
- QRadar / QRM / QVM / QNI 7.4.0 GA [5] (SFS)  
- QRadar / QRM / QVM / QRIF / QNI 7.3.3 Patch 3 [6] (SFS)  
- QRadar / QRM / QVM / QRIF / QNI 7.3.2 Patch 7 [7] (SFS)  
- QRadar Incident Forensics 7.4.0 [8] (ISO)  
- QRadar Incident Forensics 7.4.0 [9] (SFS)  
  
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Introduction  
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QRadar [10] is IBM's enterprise SIEM [11] solution. A free version of  
QRadar is available that is known as QRadar Community Edition [4]. This  
version is limited to 50 events per second and 5,000 network flows a  
minute, supports apps, but is based on a smaller footprint for  
non-enterprise use.  
  
The QRadar web application contains functionality to render various  
graphs. The graph that needs to be rendered is based on user-supplied  
request parameters. The correct graph and dataset classes are  
dynamically loaded based on these parameters. No validation is performed  
on the user-supplied parameters, allowing authenticated users to  
instantiate arbitrary classes, which can be exploited to perform various  
attacks including Server-Side Request Forgery and (potentially)  
arbitrary execution of code via specially crafted Phar files [12].  
  
In case a dataset class is provided that has not been declared (loaded)  
yet. The code tries to include the correct PHP file in which the class  
is defined. The file name of the include file is also based on the same  
request parameter. Consequently, the web application is vulnerable to  
local file inclusion.  
  
If an attacker manages to place an arbitrary PHP file on the local  
system, it is possible to abuse this issue to run arbitrary PHP code. It  
was found that the case upload functionality allows uploading of PHP  
files to a known location, thus allowing for the execution of arbitrary  
PHP code. This code will be executed with the privileges of the Apache  
system user (generally the nobody user).  
  
  
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Details  
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These issues are present in the graphs.php file. This PHP file accepts a  
number of request parameters, including chart, dataset, and  
output_image.  
  
/opt/ibm/forensics/html/graphs.php:  
$chart = ( isset($_REQUEST['chart']) ?  
htmlspecialchars($_REQUEST['chart']) : null );  
$dataClass = ( isset($_REQUEST['dataset']) ?  
htmlspecialchars($_REQUEST['dataset']) : null );  
$output_image = ( isset($_REQUEST['output_image']) ?  
$_REQUEST['output_image'] : null );  
  
If the output_image parameter is set to true, the PHP code will directly  
try to instantiate an object with the name provided in the chart  
parameter. One argument is passed to the constructor for which its value  
is obtain from a request parameter with the same name as the selected  
class name. If the class is successfully loaded, the drawChart() method  
is called - regardless of whether this method actually exists.  
  
/opt/ibm/forensics/html/graphs.php:  
// Present the data  
$cparams = $_REQUEST[$chart];  
$cs = new $chart($cparams);  
if($cs)  
$cs->drawChart();  
  
No validation is performed on the user-supplied input, allowing for  
authenticated attackers to instantiate practically any object in scope  
of the page. In addition, the first argument that is passed to the  
constructor is also controlled by the attacker.  
  
What an attacker might do depends on the class that is instantiated and  
the code that is executed by the constructor. A possible attack scenario  
would be to perform a Server-Side Request Forgery attack by  
instantiating a class that calls a method supporting one of the built-in  
PHP wrappers [13].  
  
Several classes exists in the Forensics code base, like the  
DistribConfigHelper class. There are also built-in PHP classes that are  
in scope and also allow for Server-Side Request Forgery, like the  
SplFileObject [14] class. For example:  
  
https://<ip>/forensics/graphs.php?chart=DistribConfigHelper&DistribConfigHelper=https://127.0.0.1/&output_image=1  
https://<ip>/forensics/graphs.php?chart=SplFileObject&SplFileObject=https://127.0.0.1/&output_image=1  
https://<ip>/forensics/graphs.php?chart=SplFileObject&SplFileObject=php://filter/read=string.toupper/resource=https://127.0.0.1/&output_image=1  
  
Using the same PHP wrappers it is also possible to load arbitrary Phar  
[15] files from the local machine. A known attack [12] (by Sam Thomas  
[16]) exists where an attacker can trigger PHP objects to be  
deserialized when a Phar file is loaded. Although code execution through  
deserialization is possible in the Forensics application, exploiting  
this issue is not that trivial. In particular, the attack can only be  
executed from an object with a __wakeup() or __destruct() PHP magic  
method [17]. The classes in scope of the vulnerable page don't appear to  
have suitable magic methods that could be used to execute an exploit  
(POP) chain.  
  
Besides finding a suitable magic method, exploiting the Phar wrapper  
also requires that the attacker can place a Phar file on the target  
systems as Phar files can't be loaded from remote locations. It was  
found that the case upload functionality allows uploading of files to a  
known location. However, since the graph page also contains a local file  
inclusion vulnerability, it makes more sense to target that  
vulnerability instead.  
  
The vulnerable code is executed in case the output_image request  
parameter isn't present or is set to false. In this case the requested  
class name is provided in the dataset request parameter. If this class  
isn't (yet) in scope of the PHP page, an attempt is made to load it.  
This is done by iterating though a list of predefined folder names, if a  
file exists with the same name of the requested class, it will be  
included after another which check is done to see if the class is in  
scope.  
  
/opt/ibm/forensics/html/graphs.php:  
$haveDataClass = class_exists($dataClass);  
if(!$haveDataClass) {  
foreach(array('', $DEJAVU_URL. 'Reports/','reports/') as $path) {  
$module = $path . $dataClass . ".php";  
if(file_exists($module)) {  
try {  
require_once($module);  
$haveDataClass = class_exists($dataClass);  
if($haveDataClass)  
break;  
} catch (Exception $e) {  
// Do nothing  
$msg = $e->getMessage();  
}  
}  
}  
  
As no validation is done on the class name, it is possible to include  
files outside of these folder using path traversal. However this isn't  
really needed as the first folder that is searched is empty, thus  
allowing for absolute path names. In addition, it is also possible to  
provide URL type paths. The call to file_exists() will block most PHP  
wrappers. Some built-in wrappers will pass through the file_exists()  
call, including the ftp:// [18] and ssh2.sftp:// [19] wrappers. In  
theory, it should be able to include a file over (S)FTP were it not that  
including files from remote locations has been disabled in the PHP  
configuration.  
  
/etc/php.ini:  
; http://php.net/allow-url-include  
allow_url_include = Off  
  
Because it is possible to upload arbitrary files via the case upload  
functionality, it is not that difficult to run arbitrary PHP code  
regardless of these restrictions. Although other methods also exists, we  
can just upload a PHP file to a known location and abuse this local file  
inclusion vulnerability to execute the uploaded file.  
  
------------------------------------------------------------------------  
References  
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[1] https://www.securify.nl/advisory/SFY20200407/arbitrary-class-instantiation-_-local-file-inclusion-vulnerability-in-qradar-forensics-web-application.html  
[2] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-4272  
[3] https://www.ibm.com/support/pages/node/6189645  
[4] https://developer.ibm.com/qradar/ce/  
[5] https://www.ibm.com/support/fixcentral/swg/downloadFixes?parent=IBM%20Security&product=ibm/Other+software/IBM+Security+QRadar+SIEM&release=7.4.0&platform=Linux&function=fixId&fixids=7.4.0-QRADAR-QRSIEM-20200304205308&includeRequisites=1&includeSupersedes=0&downloadMethod=http  
[6] https://www.ibm.com/support/fixcentral/swg/downloadFixes?parent=IBM%20Security&product=ibm/Other+software/IBM+Security+QRadar+SIEM&release=7.3.0&platform=Linux&function=fixId&fixids=7.3.3-QRADAR-QRSIEM-20200409085709&includeRequisites=1&includeSupersedes=0&downloadMethod=http  
[7] https://www.ibm.com/support/fixcentral/swg/downloadFixes?parent=IBM%20Security&product=ibm/Other+software/IBM+Security+QRadar+SIEM&release=7.3.0&platform=Linux&function=fixId&fixids=7.3.2-QRADAR-QRSIEM-20200406171249&includeRequisites=1&includeSupersedes=0&downloadMethod=http  
[8] https://www.ibm.com/support/fixcentral/swg/downloadFixes?parent=IBM%20Security&product=ibm/Other+software/IBM+Security+QRadar+Incident+Forensics&release=7.4.0&platform=Linux&function=fixId&fixids=7.4.0-QRADAR-QIFFULL-2019.18.0.20200304205308&includeRequisites=1&includeSupersedes=0&downloadMethod=http  
[9] https://www.ibm.com/support/fixcentral/swg/downloadFixes?parent=IBM%20Security&product=ibm/Other+software/IBM+Security+QRadar+Incident+Forensics&release=7.4.0&platform=Linux&function=fixId&fixids=7.4.0-QRADAR-QIFSFS-2019.18.0.20200304205308&includeRequisites=1&includeSupersedes=0&downloadMethod=http  
[10] https://www.ibm.com/security/security-intelligence/qradar  
[11] https://en.wikipedia.org/wiki/Security_information_and_event_management  
[12] https://github.com/s-n-t/presentations/blob/master/us-18-Thomas-It's-A-PHP-Unserialization-Vulnerability-Jim-But-Not-As-We-Know-It.pdf  
[13] https://www.php.net/manual/en/wrappers.php  
[14] https://www.php.net/manual/en/splfileobject.construct.php  
[15] https://www.php.net/manual/en/book.phar.php  
[16] https://twitter.com/_s_n_t  
[17] https://www.php.net/manual/en/language.oop5.magic.php  
[18] https://www.php.net/manual/en/wrappers.ftp.php  
[19] https://www.php.net/manual/en/wrappers.ssh2.php  
  
  
  
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