CVE-2016-8339 in Redis
Summary
by MITRE
A buffer overflow in Redis 3.2.x prior to 3.2.4 causes arbitrary code execution when a crafted command is sent. An out of bounds write vulnerability exists in the handling of the client-output-buffer-limit option during the CONFIG SET command for the Redis data structure store. A crafted CONFIG SET command can lead to an out of bounds write potentially resulting in code execution.
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Analysis
by VulDB Data Team • 09/28/2022
The vulnerability identified as CVE-2016-8339 represents a critical buffer overflow flaw within Redis database software versions 3.2.x prior to 3.2.4. This security weakness stems from inadequate input validation during the processing of client output buffer limit configurations, specifically when handling the CONFIG SET command. The flaw manifests as an out of bounds write condition that can be exploited by malicious actors to execute arbitrary code on affected systems. The vulnerability impacts Redis installations where the client-output-buffer-limit configuration option is utilized, making it particularly dangerous in environments where Redis serves as a core data storage component for applications requiring high performance and low latency.
The technical implementation of this vulnerability resides in the Redis configuration handling mechanism, specifically within the code responsible for processing the CONFIG SET command with client-output-buffer-limit parameters. When a crafted payload is sent to the Redis server through this command, the software fails to properly validate the size and boundaries of the input data before writing to memory locations. This improper bounds checking creates an opportunity for attackers to overwrite adjacent memory regions, potentially allowing them to manipulate program execution flow and inject malicious code. The vulnerability operates at the application layer and requires authentication to the Redis instance, though it can be exploited by attackers who have already gained access to the system or have discovered valid credentials.
The operational impact of CVE-2016-8339 extends beyond simple data corruption or service disruption, as it provides a pathway for complete system compromise. Attackers exploiting this vulnerability can achieve arbitrary code execution, which may lead to privilege escalation, data exfiltration, or further lateral movement within network environments. The affected Redis installations become vulnerable to remote code execution attacks, particularly in scenarios where Redis is configured with default settings or where weak authentication mechanisms exist. Organizations utilizing Redis for caching, session storage, or real-time data processing are at significant risk, as this vulnerability can be leveraged to gain unauthorized access to sensitive data stored in the database. The vulnerability's exploitation potential aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where adversaries can execute malicious commands through the compromised Redis instance.
Mitigation strategies for CVE-2016-8339 primarily focus on immediate software updates to Redis version 3.2.4 or later, which contains the necessary patches to address the buffer overflow condition. Organizations should implement network segmentation to limit access to Redis instances and ensure that only authorized systems can communicate with these databases. Additional protective measures include disabling the CONFIG SET command for non-privileged users, implementing strong authentication mechanisms, and monitoring for unusual configuration changes or command execution patterns. Security teams should also consider implementing intrusion detection systems to identify potential exploitation attempts and regularly audit Redis configuration files for unauthorized modifications. The vulnerability demonstrates the importance of proper input validation and bounds checking in preventing out of bounds write conditions, which are classified under CWE-121 as "Stack-based Buffer Overflow" and CWE-787 as "Out-of-bounds Write." Organizations should also review their Redis deployment configurations to ensure that client-output-buffer-limit settings are properly constrained and validated to prevent exploitation of similar vulnerabilities in the future.