attack-surface.md

Attack Surface Analysis for wg/wrk

Attack Surface: Lua Script Injection and Sandbox Escape

• Description: Exploiting weaknesses in wrk's Lua scripting environment to bypass security restrictions and execute arbitrary code on the system running wrk. This allows attackers to gain unauthorized control or access sensitive information.
• How wrk contributes to the attack surface: wrk integrates Lua scripting for request customization and response handling. If the Lua sandbox is not robust, or if vulnerabilities exist in its implementation within wrk, malicious Lua scripts can escape confinement.
• Example: A crafted Lua script leverages a vulnerability in wrk's Lua sandbox to execute system commands, creating a reverse shell back to the attacker's machine from the system running wrk.
• Impact: Critical. Full system compromise of the machine running wrk, potentially leading to data breaches, lateral movement within the network, and complete loss of confidentiality, integrity, and availability of the affected system.
• Risk Severity: Critical
• Mitigation Strategies:
  • Disable Lua Scripting: If Lua scripting is not absolutely necessary for your load testing needs, disable it entirely in wrk's build or configuration to eliminate this critical attack vector.
  • Restrict Lua Script Usage to Trusted Users: Limit the ability to use Lua scripts with wrk to only highly trusted and security-aware personnel.
  • Mandatory Code Review for Lua Scripts: Implement a strict code review process for all custom Lua scripts used with wrk, focusing on identifying potential malicious code or sandbox escape attempts.
  • Run wrk in Isolated Environments: Execute wrk processes in isolated environments (e.g., containers, virtual machines) with minimal privileges to limit the impact of a successful sandbox escape.
  • Regularly Update wrk: Keep wrk updated to the latest version, as updates may include security patches for Lua sandbox vulnerabilities or the embedded Lua interpreter.

Attack Surface: Buffer Overflow/Memory Corruption in wrk Code

• Description: Exploiting memory safety vulnerabilities (buffer overflows, heap overflows, etc.) in wrk's C codebase. Successful exploitation can lead to arbitrary code execution, allowing attackers to take complete control of the wrk process and potentially the underlying system.
• How wrk contributes to the attack surface: wrk is written in C, a language known for memory management challenges. Vulnerabilities can arise in request/response parsing, connection handling, or internal data structures if bounds checking or memory allocation is not handled correctly.
• Example: A specially crafted, oversized HTTP header in a server response triggers a buffer overflow in wrk's header parsing routine. This overflow is exploited to overwrite the return address on the stack, redirecting execution to attacker-controlled code.
• Impact: Critical. Remote Code Execution (RCE) on the system running wrk. Attackers can gain full control of the system, install malware, steal data, or use it as a staging point for further attacks.
• Risk Severity: Critical
• Mitigation Strategies:
  • Keep wrk Updated: Regularly update wrk to the latest version. Security patches for memory corruption vulnerabilities are often included in updates.
  • Compile with Memory Safety Tools: When building wrk from source, compile it with memory safety tools like AddressSanitizer (ASan) and MemorySanitizer (MSan) during development and testing to detect memory errors early.
  • Static Code Analysis: Utilize static code analysis tools to scan the wrk codebase for potential buffer overflows and other memory safety issues.
  • Security Code Audits: Conduct periodic security code audits of wrk's C code, focusing on memory management and input handling routines.
  • Input Fuzzing: Employ fuzzing techniques to test wrk's robustness against malformed or unexpected inputs, which can help uncover buffer overflows and other vulnerabilities.

Attack Surface: Integer Overflow/Underflow Leading to Exploitable Conditions

• Description: Exploiting integer overflow or underflow vulnerabilities in wrk's C code that result in unexpected behavior, memory corruption, or other exploitable states. While integer overflows themselves might not directly lead to RCE, they can create conditions that enable other vulnerabilities.
• How wrk contributes to the attack surface: Integer overflows/underflows can occur in calculations related to request sizes, connection counts, timers, or other numerical operations within wrk. If not properly handled, these errors can lead to incorrect memory allocation, buffer overflows, or other exploitable conditions.
• Example: An attacker provides an extremely large value for the number of connections, causing an integer overflow when wrk calculates memory allocation for connection structures. This overflow results in a heap buffer overflow when wrk attempts to write connection data into the undersized buffer.
• Impact: High. Can lead to memory corruption, denial of service, or potentially remote code execution if the integer overflow creates conditions for other exploitable vulnerabilities like buffer overflows.
• Risk Severity: High
• Mitigation Strategies:
  • Code Review for Integer Handling: Conduct thorough code reviews of wrk's C code, specifically focusing on integer arithmetic operations and ensuring proper handling of potential overflows and underflows.
  • Use Safe Integer Libraries (if applicable): Consider using safe integer libraries or compiler features that provide overflow/underflow detection or prevention during development.
  • Input Validation and Range Checks: Implement robust input validation and range checks for all numerical inputs provided to wrk (e.g., number of threads, connections, duration) to prevent excessively large or small values that could trigger overflows/underflows.
  • Testing with Boundary and Extreme Values: Test wrk extensively with boundary and extreme input values to identify potential integer handling issues and ensure robust error handling.

Attack Surface: Path Traversal Allowing Arbitrary Script Execution

• Description: Exploiting path traversal vulnerabilities in how wrk handles script paths, allowing an attacker to load and execute arbitrary Lua scripts from outside the intended script directory. This can lead to arbitrary code execution with the privileges of the wrk process.
• How wrk contributes to the attack surface: If wrk allows specifying script paths via command-line arguments or configuration without sufficient validation, attackers can use path traversal sequences (e.g., ../../) to bypass directory restrictions and load scripts from anywhere on the file system.
• Example: An attacker provides a script path like /../../../../tmp/malicious_script.lua to wrk. If wrk does not properly sanitize the path, it loads and executes the malicious script from the /tmp directory, potentially granting the attacker control over the wrk process.
• Impact: High. Arbitrary code execution on the system running wrk. Attackers can execute malicious code with the privileges of the wrk process, potentially leading to system compromise, data theft, or denial of service.
• Risk Severity: High
• Mitigation Strategies:
  • Strict Path Validation and Sanitization: Implement rigorous path validation and sanitization for all script paths provided to wrk. Sanitize input to remove path traversal sequences.
  • Restrict Script Directories (Whitelist): Configure wrk to only load scripts from a specific, whitelisted directory. Disallow loading scripts from user-provided arbitrary paths.
  • Principle of Least Privilege for File Access: Run wrk processes with minimal file system permissions, limiting the potential damage if a path traversal vulnerability is exploited.
  • Avoid User-Supplied Script Paths (if possible): If feasible, avoid allowing users to directly specify script paths. Pre-define a set of allowed scripts or script locations that are managed and controlled by administrators.