CVE-2015-2995 in Help Desk
Summary
by MITRE
SysAid Help Desk before 15.2 does not properly check file extensions, which allows remote attackers to upload and execute arbitrary files via a NULL byte after the extension, as demonstrated by a .war%00 file.
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Analysis
by VulDB Data Team • 08/15/2024
The vulnerability identified as CVE-2015-2995 affects SysAid Help Desk versions prior to 15.2, representing a critical security flaw in the application's file upload validation mechanism. This issue stems from insufficient input sanitization and improper file extension verification processes that fail to adequately handle special characters within file names. The vulnerability specifically targets the application's inability to properly parse file extensions when NULL bytes are present, creating a dangerous pathway for malicious actors to bypass security controls and execute arbitrary code on the affected system.
The technical exploitation of this vulnerability occurs through a carefully crafted file upload attack that leverages NULL byte injection techniques. When an attacker uploads a file with a malicious extension followed by a NULL byte such as .war%00, the system's flawed validation logic fails to properly recognize the file type and instead treats it as a valid war file. This misinterpretation allows the uploaded file to bypass security restrictions and be executed within the application's runtime environment, potentially granting attackers full control over the system. The vulnerability operates at the application layer and requires no special privileges to exploit, making it particularly dangerous for remote attackers.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with persistent access to the compromised system and potentially allows for lateral movement within the network. An attacker who successfully exploits this vulnerability could gain administrative privileges, access sensitive data, or use the compromised system as a launch point for further attacks. The vulnerability's presence in help desk software creates additional risks as these applications often contain sensitive organizational data and may have elevated privileges within the network infrastructure. This flaw directly aligns with CWE-434, which addresses improper restriction of file uploads, and represents a classic example of insecure file handling in web applications.
Mitigation strategies for CVE-2015-2995 should focus on implementing robust file validation mechanisms that properly handle special characters and enforce strict file type restrictions. Organizations should immediately upgrade to SysAid Help Desk version 15.2 or later, which contains the necessary patches to address this vulnerability. Additional protective measures include implementing proper input validation at multiple layers of the application, using whitelisting approaches for file types, and deploying web application firewalls to detect and block suspicious file upload attempts. The remediation process should also involve comprehensive security testing including penetration testing and code review to ensure that similar vulnerabilities do not exist in other parts of the application. This vulnerability demonstrates the importance of following secure coding practices and implementing defense-in-depth strategies as outlined in the mitre ATT&CK framework's application layer attack patterns, particularly focusing on the execution and privilege escalation techniques that attackers can employ through such flaws.