usd-2019-0072 | IT-Recht Kanzlei Plugin for Zen Cart

Advisory ID: usd-2019-0072
CVE Number: CVE-2020-6577
Affected Product: IT-Recht Kanzlei Plugin for Zen Cart deutsch
Affected Version: v1.5.6c (Zen Cart deutsch version)
Vulnerability Type: SQL Injection
Security Risk: Medium
Vendor: IT-Recht Kanzlei
Vendor URL: https://www.it-recht-kanzlei.de
Vendor Status: fixed

Description

The „IT-Rechtkanzlei“ module, which is included by default in German Zen Cart releases, is vulnerable to blind SQL injections. The „IT-Rechtkanzlei“ offers the possibility to distribute legal texts as PDF to various webshops via its interface. The file itrk-api.php in the root directory of webshops such as Zen Cart can get an XML in the POST parameter with the legal texts. The rechtstext_language tag is dynamically embedded into an SQL query and can be used to exploit SQL injections. But in order to exploit this vulnerability, the attacker needs a valid „IT-Rechtkanzlei“ token which is randomly generated while creating the webshop. Since the „IT-Rechtkanzlei“ has access to those tokens, the company would be able to dump or modify the database of a Zen Cart application.

Proof of Concept (PoC)

The following request results in a blind SQL injection where the rechtstext_language tag is the vulnerable parameter:

The it_recht_kanzlei_api.php file contains the vulnerability in line 105:

The query is not prepared and the $language_code variable is also not escaped. Therefore this results in a blind SQL injection flaw. A similar vulnerability occurs in line 222.

The following POST request would add a sleep of 5 seconds to the database query. Using this method, a blind SQL injection can be verified.

Fix

All statements and parameters should be prepared before executing the queries. Make sure to encode the user supplied input.

Timeline

  • 2019-12-16 Vulnerability discovered by Gerbert Roitburd and Markus Schader
  • 2020-02-14 Initial contact with vendor
  • 2020-03-06 Vulnerability details transmitted to vendor
  • 2020-03-07 Fix proposed by vendor
  • 2020-03-12 Effectiveness of fix verified by usd AG
  • 2020-03-12 Vendor informs about upcoming release containing fix
  • 2021-02-22 Retesting of released fix
  • 2021-02-26 Security advisory released

Credits

This security vulnerability was discovered by Gerbert Roitburd and Markus Schader of usd AG.

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Disclaimer

The information provided in this security advisory is provided „as is“ and without warranty of any kind. Details of this security advisory may be updated in order to provide as accurate information as possible.