CVE-2007-2431 in TCExam
Summary
by MITRE
Dynamic variable evaluation vulnerability in shared/config/tce_config.php in TCExam 4.0.011 and earlier allows remote attackers to conduct cross-site scripting (XSS) and possibly other attacks by modifying critical variables such as $_SERVER, as demonstrated by injecting web script via the _SERVER[SCRIPT_NAME] parameter.
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Analysis
by VulDB Data Team • 09/09/2024
The vulnerability identified as CVE-2007-2431 represents a critical dynamic variable evaluation flaw within the TCExam 4.0.011 and earlier versions, specifically located in the shared/config/tce_config.php file. This issue stems from the application's insecure handling of server variables, particularly the $_SERVER superglobal array, which creates an avenue for malicious actors to manipulate critical system parameters. The vulnerability manifests when the application fails to properly sanitize or validate input data before incorporating it into dynamic variable evaluations, thereby exposing the system to various forms of injection attacks. The flaw enables remote attackers to inject malicious code through the _SERVER[SCRIPT_NAME] parameter, which is processed without adequate security controls.
The technical implementation of this vulnerability involves the application's reliance on dynamic variable evaluation techniques that directly incorporate user-controllable data into server-side operations. When attackers manipulate the $_SERVER[SCRIPT_NAME] parameter, they can inject malicious scripts that get executed in the context of other users' browsers, leading to cross-site scripting attacks. This type of vulnerability falls under CWE-95, which describes improper neutralization of potentially dangerous data within code that is intended to be treated as code. The vulnerability also demonstrates characteristics of CWE-79, representing cross-site scripting flaws, where the application fails to properly sanitize user input before incorporating it into dynamic web content. The attack vector leverages the trust model between the web application and its users, as the malicious code is executed within the legitimate user context, making detection and prevention significantly more challenging.
The operational impact of CVE-2007-2431 extends beyond simple XSS attacks, as the vulnerability can potentially enable more sophisticated exploitation techniques. Attackers can leverage this flaw to execute arbitrary code, steal session cookies, perform unauthorized actions on behalf of users, or even escalate privileges within the application environment. The vulnerability affects the core configuration management system of TCExam, which means that successful exploitation could compromise the entire application's integrity and availability. The remote nature of the attack means that threat actors do not require physical access or local network presence to exploit the vulnerability, making it particularly dangerous in publicly accessible environments. This type of vulnerability also aligns with ATT&CK technique T1059, which covers command and scripting interpreter usage, as attackers can leverage the dynamic evaluation mechanism to execute malicious scripts.
Mitigation strategies for this vulnerability require immediate implementation of input validation and sanitization measures within the TCExam application. The most effective approach involves implementing strict validation of all server variables before they are processed, particularly those within the $_SERVER superglobal array. Organizations should implement proper output encoding mechanisms to prevent malicious scripts from executing in user contexts. The application should be updated to a version that addresses this specific vulnerability, as TCExam 4.0.012 and later versions include fixes that properly sanitize server variables and eliminate the dynamic evaluation patterns that enable this attack. Security measures should also include implementing Content Security Policy headers to prevent unauthorized script execution, employing web application firewalls to detect and block malicious requests, and conducting regular security assessments to identify similar dynamic evaluation patterns that could create similar vulnerabilities. Additionally, developers should follow secure coding practices that avoid dynamic variable evaluation with user-controllable inputs and implement proper input validation frameworks to prevent such issues from occurring in future implementations.