threat-modeling.md

Threat Model Analysis for redis/hiredis

Threat: Malformed Redis Response Exploitation - Buffer Overflow

Description: An attacker, by controlling or compromising the Redis server, sends a crafted Redis response containing excessively long string or array lengths. Vulnerabilities in hiredis's response parsing functions, specifically in buffer length validation, can lead to a buffer overflow when processing this response. Impact:

• Application crash (Denial of Service).
• Potentially, arbitrary code execution if the overflow overwrites critical memory regions, allowing the attacker to gain control of the application process. Hiredis Component Affected: Response parsing functions within redisReader (e.g., redisReaderFeed, redisReaderGetReply), particularly buffer management within these functions. Risk Severity: Critical Mitigation Strategies:
• Use latest hiredis version: Upgrade to the newest stable version of hiredis as these vulnerabilities are often patched in updates.
• Input validation on Redis server (if feasible): Implement measures to validate or sanitize data sent to Redis to prevent injection of malicious payloads that could be reflected in responses.
• Memory safety tools during development: Utilize memory safety tools like AddressSanitizer (ASan) and MemorySanitizer (MSan) during development and testing to proactively detect buffer overflows and memory errors.
• Operating System level protections: Ensure operating system level security features like Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) are enabled to hinder exploitation.

Threat: Malformed Redis Response Exploitation - Integer Overflow/Underflow

Description: An attacker crafts a Redis response with manipulated integer values (e.g., lengths, counts) specifically designed to trigger integer overflows or underflows during parsing within hiredis. This can result in incorrect memory allocation sizes or other unexpected program behavior. Impact:

• Unexpected application behavior and potential instability.
• Memory corruption if incorrect memory allocation leads to out-of-bounds memory access (read or write).
• Denial of Service due to crashes or resource exhaustion caused by memory corruption. Hiredis Component Affected: Response parsing functions within redisReader, specifically integer parsing and handling logic. Risk Severity: High Mitigation Strategies:
• Use latest hiredis version: Ensure you are using the most recent version of hiredis which includes fixes for potential integer overflow vulnerabilities.
• Code review of hiredis usage: Review application code to ensure it robustly handles potentially large or unusual integer values received from Redis responses and avoids assumptions about integer ranges without validation.
• Input validation on Redis server (indirect): Similar to buffer overflows, limiting the potential for malicious data injection into Redis can reduce the attack surface.

Threat: Memory Corruption in Hiredis Core Functions - Use-After-Free

Description: A vulnerability within hiredis's memory management logic can lead to a use-after-free condition. This occurs when memory is deallocated (freed), but a pointer to that memory is still used later in the program. Specific sequences of Redis commands, responses, or error conditions within hiredis could trigger this. Impact:

• Application crash (Denial of Service).
• Potentially, arbitrary code execution if the freed memory is reallocated and attacker-controlled data is placed in that memory location before the invalid pointer is used. Hiredis Component Affected: Memory management functions throughout hiredis, potentially affecting various modules depending on the specific vulnerability. Risk Severity: Critical Mitigation Strategies:
• Use latest hiredis version: Upgrade to the latest hiredis version as use-after-free vulnerabilities are frequently addressed in library updates.
• Memory safety tools during development: Utilize tools like Valgrind or AddressSanitizer during development and testing to detect use-after-free errors and other memory-related issues.
• Careful resource management in application code: Review application code to ensure proper handling of hiredis connection and context objects, minimizing the risk of triggering use-after-free conditions within hiredis.

Threat: Memory Corruption in Hiredis Core Functions - Double-Free

Description: A bug in hiredis could cause memory to be freed more than once (double-free). This corrupts memory management metadata and can lead to unpredictable and potentially exploitable behavior. Impact:

• Application crash (Denial of Service).
• Potentially, memory corruption that could be exploited to achieve arbitrary code execution by manipulating memory management structures. Hiredis Component Affected: Memory management functions within hiredis. Risk Severity: Critical Mitigation Strategies:
• Use latest hiredis version: Upgrade to the latest hiredis version to benefit from bug fixes, including those addressing double-free vulnerabilities.
• Memory safety tools during development: Use Valgrind or AddressSanitizer during testing to detect double-free errors early in the development cycle.
• Thorough testing and code review: Implement comprehensive testing and code review processes to identify and prevent potential double-free scenarios in both hiredis itself (if contributing) and in application code using hiredis.