CVE-2009-5053 in Smarty
Summary
by MITRE
Unspecified vulnerability in Smarty before 3.0.0 beta 6 allows remote attackers to execute arbitrary PHP code by injecting this code into a cache file.
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Analysis
by VulDB Data Team • 02/08/2019
The vulnerability identified as CVE-2009-5053 represents a critical security flaw in the Smarty template engine version 3.0.0 beta 5 and earlier. This issue stems from inadequate input validation and sanitization mechanisms within the caching system, creating a pathway for remote attackers to inject malicious PHP code into cache files. The vulnerability specifically affects the template processing functionality where user-supplied data is not properly escaped or validated before being written to cache storage, enabling attackers to manipulate the caching mechanism as a vector for code execution.
The technical exploitation of this vulnerability occurs through the manipulation of template variables that are subsequently cached without proper sanitization. When Smarty processes templates and stores the compiled output in cache files, attacker-controlled input can be inadvertently written to these files, creating a persistent backdoor. This flaw falls under the category of code injection vulnerabilities and is classified as CWE-94, which encompasses "Improper Control of Generation of Code ('Code Injection')." The vulnerability represents a privilege escalation issue where unauthenticated remote attackers can gain arbitrary code execution capabilities on systems running affected Smarty versions, potentially leading to complete system compromise.
The operational impact of CVE-2009-5053 extends beyond simple code execution, as it enables attackers to establish persistent access to affected systems through the cached files. This vulnerability is particularly dangerous in web applications that utilize Smarty for dynamic content generation, as it allows attackers to execute malicious code with the privileges of the web server process. The attack surface includes any application that accepts user input through template variables and utilizes Smarty's caching mechanism, making it a widespread concern for web applications deployed in production environments. The vulnerability's severity is amplified by the fact that it can be exploited without requiring authentication or special privileges, and the malicious code remains persistent across server restarts as long as the cache files exist.
Mitigation strategies for CVE-2009-5053 focus primarily on upgrading to Smarty version 3.0.0 beta 6 or later, which includes proper input sanitization and validation mechanisms for cached content. Organizations should implement comprehensive input validation procedures and ensure that all user-supplied data is properly escaped before being processed by the Smarty template engine. Additionally, the caching system should be configured with appropriate file permissions and access controls to prevent unauthorized modification of cache files. Security measures should include regular monitoring of cache directories for suspicious file modifications and implementation of automated vulnerability scanning tools to detect potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1059.007 for "Command and Scripting Interpreter: PowerShell" and T1505.003 for "Server Software Component: Web Shell," highlighting the persistent and stealthy nature of the attack vector. Organizations should also consider implementing web application firewalls and content delivery network protections to detect and block malicious template injection attempts, while maintaining regular security audits to identify and remediate similar vulnerabilities in other components of their web applications.