CVE-2023-4595 in SLmail
Summary
by MITRE • 11/23/2023
An information exposure vulnerability has been found, the exploitation of which could allow a remote user to retrieve sensitive information stored on the server such as credential files, configuration files, application files, etc., simply by appending any of the following parameters to the end of the URL: %00 %0a, %20, %2a, %a0, %aa, %c0 and %ca.
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Analysis
by VulDB Data Team • 12/16/2023
This vulnerability represents a critical information exposure flaw that fundamentally compromises server-side security through improper input validation mechanisms. The vulnerability stems from insufficient sanitization of user-supplied parameters within URL parsing routines, allowing attackers to manipulate request strings to access unauthorized server resources. The specific attack vectors involve null byte sequences and various URL encoding patterns that bypass normal access controls and directory traversal restrictions. This weakness enables remote attackers to systematically enumerate and retrieve sensitive files including credential stores, configuration data, and application source code without authentication or authorization. The vulnerability operates at the application layer and can be classified under CWE-200, which specifically addresses information exposure vulnerabilities where sensitive data is accessible to unauthorized parties. The attack surface is particularly broad as it leverages common URL encoding techniques that are typically processed transparently by web servers and applications.
The technical implementation of this vulnerability exploits the way web applications handle special character sequences within Uniform Resource Locators. When the application processes URLs containing the specified parameters such as %00 %0a, %20, %2a, %a0, %aa, %c0 and %ca, the server fails to properly validate or sanitize these inputs before executing file access operations. The null byte sequences like %00 and %0a can potentially truncate strings or manipulate path resolution algorithms, while the other encoded characters may interfere with normal request parsing and access control enforcement. This type of vulnerability is particularly dangerous because it can be exploited through simple URL manipulation without requiring complex payloads or advanced exploitation techniques. The underlying flaw lies in the application's failure to implement proper input validation, sanitization, and access control measures at the point of request processing, making it susceptible to manipulation through carefully crafted URL parameters.
The operational impact of this vulnerability extends far beyond simple data theft, as it can lead to complete system compromise and unauthorized access to sensitive infrastructure components. Attackers can systematically discover and extract credential files that may contain database passwords, API keys, and service account information, which can then be used for lateral movement within the network. Configuration files often contain sensitive settings, database connection strings, and application-specific security parameters that can facilitate further exploitation. The vulnerability also exposes application source code, which can reveal implementation details, business logic, and potential additional attack vectors. This information exposure creates a cascading effect where initial reconnaissance leads to more sophisticated attacks, including privilege escalation, data exfiltration, and system compromise. The vulnerability aligns with ATT&CK technique T1213.002, which involves data from information repositories, and represents a significant risk to confidentiality and integrity within the affected systems.
Mitigation strategies must address both the immediate input validation gaps and implement comprehensive access control mechanisms to prevent unauthorized file access. The primary remediation involves implementing strict input validation and sanitization routines that reject or properly encode special character sequences before processing user requests. Applications should employ proper parameter validation and ensure that all URL parameters are sanitized according to security best practices. Web application firewalls and security middleware should be configured to detect and block suspicious URL patterns containing the vulnerable encoding sequences. Additionally, implementing proper access controls and least privilege principles can limit the damage from successful exploitation attempts. Regular security testing including penetration testing and vulnerability scanning should be conducted to identify similar weaknesses in the application architecture. The remediation process should also include implementing proper logging and monitoring mechanisms to detect suspicious access patterns and unauthorized file access attempts. Organizations should also consider implementing automated security controls and input validation frameworks that can prevent similar vulnerabilities from being introduced during application development cycles.