Attack Surface: 1. Request Smuggling/Splitting
Description: Exploitation of discrepancies in how HTTP requests with ambiguous Transfer-Encoding, Content-Length, or chunked encoding are handled. This focuses on HttpCore's own parsing and handling, not just its interaction with other components.
HttpComponents-Core Contribution: HttpCore's internal parsing logic for Transfer-Encoding, Content-Length, and chunked encoding is the direct source of the vulnerability if it deviates from strict RFC compliance or has subtle bugs in edge-case handling.
Example: A bug in HttpCore's chunked encoding parser allows an attacker to craft a request that bypasses length checks, leading to the injection of a second, malicious request. This is distinct from a front-end/back-end discrepancy; it's a flaw within HttpCore itself.
Impact: Allows attackers to bypass security controls, access unauthorized resources, poison caches, and potentially gain control of the application.
Risk Severity: Critical
Mitigation Strategies:
* Update: Use the absolute latest patched version of HttpComponents Core. Prioritize updates addressing CVEs related to request parsing and handling.
* Configuration (HttpCore): Configure HttpCore to be as strict as possible in rejecting ambiguous or malformed requests. Examine configuration options for strict RFC compliance and header validation. Enable any available strict parsing modes. This is crucial for mitigating internal parsing issues.
* Fuzz Testing: Conduct fuzz testing specifically targeting HttpCore's request parsing functionality with malformed and edge-case inputs to identify potential vulnerabilities.
* Code Review: Manually review the relevant sections of HttpCore's source code (if accessible) that handle request parsing, looking for potential vulnerabilities.
Attack Surface: 2. HTTP/2-Specific Vulnerabilities (if using HTTP/2)
Description: Exploitation of vulnerabilities specific to the HTTP/2 protocol, such as HPACK bombing (header compression attacks), stream multiplexing issues, and flow control errors. This focuses on HttpCore's own HTTP/2 implementation.
HttpComponents-Core Contribution: HttpCore's internal implementation of the HTTP/2 protocol, including header compression (HPACK), stream management, and flow control, is the direct attack surface.
Example: A flaw in HttpCore's HPACK decompression logic allows an attacker to send a crafted request that causes excessive memory allocation, leading to a denial-of-service attack. This is a vulnerability within HttpCore's HTTP/2 implementation.
Impact: Denial of service (DoS), potentially leading to application crashes or instability.
Risk Severity: High (if HTTP/2 is used)
Mitigation Strategies:
* Update: Use the very latest patched version of HttpComponents Core, prioritizing updates that address HTTP/2-related CVEs.
* Configuration (HttpCore): Carefully review and configure HttpCore's HTTP/2 settings:
* MaxHeaderListSize: Set a strict limit on the maximum size of the header list.
* MaxConcurrentStreams: Limit the maximum number of concurrent streams to a reasonable value.
* InitialWindowSize: Configure appropriate flow control window sizes to prevent resource exhaustion.
* Fuzz Testing: Perform fuzz testing specifically targeting HttpCore's HTTP/2 implementation with various malformed and edge-case inputs.
* Code Review: If source code is available, review the HTTP/2 implementation for potential vulnerabilities.
Description: An attacker exhausts HttpCore's internal connection pool due to misconfiguration, leading to DoS. This is distinct from general connection exhaustion; it's about the pool itself being misconfigured.
HttpComponents-Core Contribution: HttpCore's connection pool and its configuration parameters (MaxTotalConnections, MaxConnectionsPerRoute) are directly responsible. The vulnerability arises from setting these values too high relative to the system's capabilities.
Example: MaxTotalConnections is set to an extremely large value (e.g., 100,000) on a system that can only handle a few thousand concurrent connections. Even a moderate number of legitimate requests could exhaust the pool and prevent further connections. This is not about an external attacker; it's about the internal limit being too high.
Impact: Denial of service (DoS) due to HttpCore's internal resource limits being exceeded.
Risk Severity: High
Mitigation Strategies:
* Tune Connection Pool Parameters: Carefully configure MaxTotalConnections and MaxConnectionsPerRoute to realistic values based on thorough testing and system resource monitoring. Start with conservative values and increase them only if necessary and with careful monitoring. Do not use excessively large values.
* Monitoring (HttpCore Specific): If HttpCore provides metrics or logging for its connection pool (e.g., number of active connections, number of idle connections, number of pending requests), monitor these closely to detect exhaustion or near-exhaustion conditions.
* Stress Testing: Perform stress testing to determine the actual limits of the system and HttpCore's connection pool under realistic load conditions.