CVE-2016-10517 in Redis
Summary
by MITRE
networking.c in Redis before 3.2.7 allows "Cross Protocol Scripting" because it lacks a check for POST and Host: strings, which are not valid in the Redis protocol (but commonly occur when an attack triggers an HTTP request to the Redis TCP port).
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Analysis
by VulDB Data Team • 01/04/2023
The vulnerability identified as CVE-2016-10517 represents a critical cross-protocol scripting flaw in Redis versions prior to 3.2.7 that fundamentally undermines the security model of the database system. This vulnerability arises from the lack of proper protocol validation within Redis's networking component, specifically in the networking.c file, which fails to properly validate incoming requests based on the expected Redis protocol format. The flaw allows attackers to exploit the absence of checks for HTTP-specific elements such as POST method indicators and Host header strings that are entirely foreign to the Redis protocol but commonly present in HTTP requests.
The technical exploitation of this vulnerability occurs when an attacker can direct an HTTP request to a Redis server's TCP port, typically port 6379, which is the default port used by Redis for client connections. The Redis server processes these requests without proper validation, treating HTTP headers and methods as if they were legitimate Redis protocol commands. This creates a scenario where an attacker can potentially inject malicious commands through HTTP requests that are sent to the Redis port, effectively bypassing the normal Redis protocol validation mechanisms. The vulnerability is particularly dangerous because it allows an attacker to leverage the HTTP protocol to interact with Redis, which is designed to operate using its own binary protocol.
From an operational impact perspective, this vulnerability enables attackers to perform cross-protocol scripting attacks that can lead to complete system compromise. An attacker can exploit this flaw to execute arbitrary commands on the Redis server, potentially leading to data exfiltration, data corruption, or unauthorized access to sensitive information stored within the Redis database. The vulnerability is especially concerning in environments where Redis is deployed without proper network segmentation or authentication controls, as it can be exploited remotely without requiring prior authentication. This makes it a particularly attractive target for automated scanning and exploitation tools that can identify and exploit Redis instances exposed to the internet.
The security implications of this vulnerability extend beyond simple command execution, as it represents a fundamental failure in protocol validation that can be exploited to bypass multiple security controls. According to CWE classification, this vulnerability aligns with CWE-444, which describes "Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')", although the specific context differs from traditional HTTP smuggling attacks. The vulnerability also maps to ATT&CK technique T1071.004, which covers "Application Layer Protocol: DNS", as it exploits the misinterpretation of protocol elements to gain unauthorized access. The lack of proper input validation in the networking component creates a pathway for attackers to leverage HTTP request patterns to manipulate Redis operations, fundamentally compromising the integrity of the database server.
The recommended mitigations for this vulnerability include immediate upgrade to Redis version 3.2.7 or later, where the protocol validation has been strengthened to properly reject HTTP-specific elements. Organizations should also implement proper network segmentation to prevent direct exposure of Redis ports to untrusted networks, deploy firewall rules to restrict access to Redis ports, and ensure that Redis instances are properly configured with authentication and encryption. Additionally, network monitoring should be implemented to detect unusual patterns of traffic that might indicate exploitation attempts, and regular security assessments should be conducted to identify and remediate similar protocol validation weaknesses in other network services. The vulnerability serves as a reminder of the importance of proper protocol validation in network services and demonstrates how seemingly minor implementation gaps can lead to severe security consequences.