SEC Consult Vulnerability Lab Security Advisory < 20180906-0 > ======================================================================= title: CSV Formula Injection product: DokuWiki vulnerable version: 2018-04-22a "Greebo" and older versions fixed version: None CVE number: CVE-2018-15474 impact: Medium homepage: https://www.dokuwiki.org found: 2018-07-09 by: Jean-Benjamin Rousseau (Office Zurich) SEC Consult Vulnerability Lab An integrated part of SEC Consult Europe | Asia | North America https://www.sec-consult.com ======================================================================= Vendor description: ------------------- "DokuWiki is a simple to use and highly versatile Open Source wiki software that doesn't require a database. It is loved by users for its clean and readable syntax. The ease of maintenance, backup and integration makes it an administrator's favorite. Built in access controls and authentication connectors make DokuWiki especially useful in the enterprise context and the large number of plugins contributed by its vibrant community allow for a broad range of use cases beyond a traditional wiki." Source: https://www.dokuwiki.org/dokuwiki Business recommendation: ------------------------ The issue will not be fixed according to the vendor. Users are advised to be careful when opening files via the CSV export functionality. SEC Consult recommends to perform a thorough security review conducted by security professionals to identify and resolve all security issues. Vulnerability overview/description: ----------------------------------- 1) CSV Formula Injection vulnerability The administration panel of the application has a "CSV export of users" feature which allows the export of user data (username, real name, email address and user groups) as a CSV file. On the registration page, it is possible for an attacker to set certain values in the Real Name field that - when exported and opened with a spreadsheet application (Microsoft Excel, Open Office, etc.) - will be interpreted as a formula. This puts the administrators who open those malicious exported files at risk. Exfiltration of sensitive data or even the execution of arbitrary code on the local machine of the victim will be the result. The final impact depends on the used spreadsheet software on the client of the victim. Proof of concept: ----------------- 1) CSV Formula Injection vulnerability Registration URL: http://www.example.com/doku.php?id=start&do=register When the registration request is submitted, the following parameters are sent in a POST request: sectok=&do=register&save=1&login=login_parameter&fullname=evil_csv_formula_injection_payload&email=email_address The "fullname" parameter is not sanitized before being stored and during the CSV export. An attacker can inject different CSV formula payloads in the fullname parameter. For example: =cmd|'/C calc'!A0 As soon as the file gets opened in Microsoft Excel, the program calc.exe is launched. Different warnings might pop up. However, these warnings are usually ignored because the file comes from a trusted source. Vulnerable / tested versions: ----------------------------- The latest version 2018-04-22a "Greebo" has been tested: https://download.dokuwiki.org/out/dokuwiki-8a269cc015a64b40e4c918699f1e1142.tgz Also found to be vulnerable: 2017-02-19 stable release 2016-06-26 stable release 2015-08-10 stable release 2014-09-29 stable release 2014-05-05 stable release 2013-12-08 stable release Vendor contact timeline: ------------------------ 2018-07-18: Contacting vendor through andi@splitbrain.org 2018-07-18: Vendor replied, they asked for the advisory without encryption 2018-07-19: Advisory sent without encryption 2018-07-19: Vendor replied with no intention to fix the vulnerability 2018-07-30: Reminder sent to the vendor. No reply 2018-08-20: Ask for updates to the vendor 2018-08-20: Vendor replied that no patch will be provided 2018-09-06: Public release of security advisory Solution: --------- The issue will not be fixed according to the vendor: https://github.com/splitbrain/dokuwiki/issues/2450 Workaround: ----------- None Advisory URL: ------------- https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SEC Consult Vulnerability Lab SEC Consult Europe | Asia | North America About SEC Consult Vulnerability Lab The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. 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. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Interested to work with the experts of SEC Consult? Send us your application https://www.sec-consult.com/en/career/index.html Interested in improving your cyber security with the experts of SEC Consult? Contact our local offices https://www.sec-consult.com/en/contact/index.html ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mail: research at sec-consult dot com Web: https://www.sec-consult.com Blog: http://blog.sec-consult.com Twitter: https://twitter.com/sec_consult EOF Jean-Benjamin Rousseau / @2018