CVE-2016-10322 in Photo Station
Summary
by MITRE
Synology Photo Station before 6.3-2958 allows remote authenticated guest users to execute arbitrary commands via shell metacharacters in the X-Forwarded-For HTTP header to photo/login.php.
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Analysis
by VulDB Data Team • 08/28/2020
This vulnerability exists in Synology Photo Station versions prior to 6.3-2958 and represents a critical command injection flaw that can be exploited by authenticated guest users. The vulnerability stems from improper input validation in the photo/login.php script where the X-Forwarded-For HTTP header is processed without adequate sanitization. When a guest user with valid authentication attempts to log in, the application fails to properly escape or filter special shell metacharacters present in the X-Forwarded-For header, creating an opportunity for arbitrary command execution. This flaw falls under CWE-78 which specifically addresses improper neutralization of special elements used in OS commands, making it a direct instance of OS command injection. The vulnerability is particularly concerning because it requires only guest authentication, which is often less restricted than standard user accounts, and allows attackers to execute commands with the privileges of the web server process.
The operational impact of this vulnerability extends beyond simple command execution as it provides attackers with a persistent backdoor into the system. An attacker who gains access through this vulnerability can potentially escalate privileges, access sensitive data, modify system configurations, or even establish persistence mechanisms. The X-Forwarded-For header is commonly used in web applications for logging and tracking purposes, making it a legitimate part of the HTTP communication that is often not subject to strict input validation. This makes the vulnerability particularly stealthy and difficult to detect through standard network monitoring. The attack vector is relatively simple to exploit, requiring only a single HTTP request with a specially crafted X-Forwarded-For header containing shell metacharacters such as semicolons, ampersands, or backticks. This vulnerability aligns with ATT&CK technique T1059.001 which covers command and scripting interpreter, specifically focusing on the execution of system commands through legitimate system tools.
The technical implementation of this vulnerability demonstrates a classic case of insufficient input sanitization in web applications. When the application processes the X-Forwarded-For header in the login script, it likely concatenates this value into a system command without proper escaping or encoding of special shell characters. This creates an environment where attackers can inject malicious commands that will be executed by the underlying operating system. The guest user authentication requirement significantly reduces the barrier to exploitation, as guest accounts are often created for temporary access or demonstration purposes. Organizations using Synology Photo Station should immediately implement security patches to address this vulnerability, as the combination of remote execution capability and minimal authentication requirements makes it highly attractive to threat actors. The vulnerability also highlights the importance of proper input validation across all HTTP headers and parameters, particularly those that are not typically subject to strict sanitization in web applications. Security best practices dictate that all user-provided data should be treated as untrusted and properly escaped before being used in system commands or database queries.