CVE-2023-2017 in Shopware
Summary
by MITRE • 04/17/2023
Server-side Template Injection (SSTI) in Shopware 6 (<= v6.4.20.0, v6.5.0.0-rc1 <= v6.5.0.0-rc4), affecting both shopware/core and shopware/platform GitHub repositories, allows remote attackers with access to a Twig environment without the Sandbox extension to bypass the validation checks in `Shopware\Core\Framework\Adapter\Twig\SecurityExtension` and call any arbitrary PHP function and thus execute arbitrary code/commands via usage of fully-qualified names, supplied as array of strings, when referencing callables. Users are advised to upgrade to v6.4.20.1 to resolve this issue. This is a bypass of CVE-2023-22731.
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Analysis
by VulDB Data Team • 04/17/2023
Server-side template injection vulnerabilities represent a critical class of security flaws that allow attackers to execute arbitrary code on vulnerable systems. The vulnerability identified as CVE-2023-2017 affects Shopware 6 versions up to and including v6.4.20.0 and v6.5.0.0-rc4, specifically targeting the Twig templating engine implementation within the shopware/core and shopware/platform repositories. This vulnerability operates at the intersection of template processing and code execution, creating a pathway for remote attackers to bypass existing security controls and gain unauthorized system access.
The technical flaw resides in the `Shopware\Core\Framework\Adapter\Twig\SecurityExtension` component which is designed to validate and restrict template execution to prevent dangerous operations. However, attackers can exploit a specific bypass mechanism that allows them to supply fully-qualified names as array of strings when referencing callables. This approach circumvents the validation checks that should normally prevent execution of arbitrary PHP functions. The vulnerability specifically targets the security sandbox mechanism that is supposed to restrict template access to dangerous functions, but the flaw enables attackers to call any arbitrary PHP function directly from the template context. This bypass technique represents a sophisticated attack vector that leverages the underlying architecture of the Twig environment to execute malicious payloads without proper authorization.
The operational impact of this vulnerability is severe and far-reaching for affected systems. Remote attackers with access to a Twig environment without the Sandbox extension can execute arbitrary code and commands on the affected server, potentially leading to complete system compromise. This vulnerability allows attackers to perform actions such as reading sensitive files, executing shell commands, establishing backdoors, and accessing database contents. The implications extend beyond simple code execution to include potential data breaches, service disruption, and unauthorized access to business-critical systems. Organizations running affected Shopware versions face significant risk of unauthorized access and potential exploitation for further attacks within their network infrastructure. The vulnerability's classification aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and falls under the ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell," though the actual exploitation occurs through PHP code execution rather than PowerShell specifically.
Organizations should immediately upgrade to Shopware version 6.4.20.1 to resolve this vulnerability, as this patch addresses the bypass mechanism that allows attackers to circumvent the security validation checks. The upgrade process should be prioritized and tested in staging environments before deployment to production systems. Additionally, organizations should implement network-level monitoring to detect suspicious template processing activities and consider temporary network segmentation to limit the potential impact if exploitation occurs. Security teams should also review their current template validation policies and ensure that no unauthorized access to template environments exists, particularly for users who might have access to the Twig environment without proper sandbox restrictions. The vulnerability demonstrates the importance of maintaining proper security boundaries and validating all inputs within template processing systems, as the bypass mechanism relies on the absence of proper sandbox enforcement within the Twig environment.