HTTP Response Splitting
HTTP Response Splitting is a web application vulnerability that allows attackers to manipulate a server's response to inject malicious data into HTTP headers, ultimately controlling the content of the response sent back to the user. This can lead to attacks, including cross-site scripting (XSS) and cache poisoning.
Here's how it works:
Vulnerable Input: The application allows user-supplied data to be included in HTTP response headers without proper validation or sanitization.
Injection of CRLF Characters: Attackers inject carriage return (CR) and line feed (LF) characters into the user input. These characters are used to separate HTTP headers and signify the end of a line.
Manipulating the Response: By injecting CRLF characters, the attacker can create or modify new headers, splitting the HTTP response into multiple parts.
Malicious Actions: This allows the attacker to:
Inject Malicious Scripts: Insert scripts into the response body, leading to XSS attacks when the user's browser executes the script.
Poison Caches: Manipulate cache-control headers to poison web caches, forcing users to download malicious content.
Hijack Sessions: Set cookies with malicious values to hijack user sessions.
Redirect Users: Redirect users to malicious websites by manipulating the
Locationheader.
Example:
Imagine a web application that uses a user-supplied parameter to set a cookie in the HTTP response:
Set-Cookie: UserID= + user_inputAn attacker could inject the following input:
attacker_input; path=/; HttpOnly%0d%0aSet-Cookie: EvilCookie=attackervalueThis input includes CRLF characters (%0d%0a) that split the response, setting a second malicious cookie (EvilCookie).
Consequences of HTTP Response Splitting:
Data Theft: XSS attacks can steal user credentials, session cookies, and sensitive information.
Website Defacement: Attackers can modify the website's content displayed to users.
Reputation Damage: Successful attacks can damage the website's reputation and erode user trust.
Preventing HTTP Response Splitting:
Input Validation and Sanitization: Strictly validate and sanitize all user input before including it in HTTP response headers.
Output Encoding: Encode output data to prevent the interpretation of special characters.
Use a Web Application Firewall (WAF): A WAF can help detect and block HTTP response-splitting attacks.
Regular Security Testing: Conduct regular security assessments and penetration testing to identify and address vulnerabilities.
By understanding and mitigating HTTP response splitting vulnerabilities, organizations can significantly enhance the security of their web applications and protect users from attacks.
ThreatNG is a powerful ally in the fight against HTTP Response Splitting vulnerabilities. While it doesn't directly exploit these vulnerabilities like a dedicated penetration testing tool, its comprehensive approach to external attack surface management allows it to identify potential weaknesses and misconfigurations that could make an application susceptible to this attack. By proactively highlighting these risks, ThreatNG empowers organizations to take corrective action and strengthen their web application security.
1. Identifying Potential for HTTP Response Splitting:
Exposed APIs and Development Environments: Identifying exposed APIs and development environments can reveal potential areas where user input might be reflected in HTTP responses. This helps prioritize further investigation for potential response-splitting vulnerabilities.
Known Vulnerabilities: ThreatNG's vulnerability database can help identify known vulnerabilities associated with web servers and frameworks the organization uses. If the application uses components with known vulnerabilities related to input validation or output encoding, it could indicate a higher risk of response splitting.
Exposed Code and Configurations: Analyzing exposed code repositories can reveal insecure coding practices for handling user input and generating HTTP responses. This can help identify potential areas where response splitting might be possible.
Exposed Sensitive Information: If ThreatNG finds sensitive information like error messages or debugging output through search engine exploitation, it might suggest inadequate input validation or output encoding, which are crucial for preventing response splitting.
Past Vulnerabilities: Analyzing archived web pages can reveal a history of vulnerabilities, including response splitting or related issues like XSS. This can provide insights into recurring patterns of security weaknesses.
2. Mitigating Risks Related to HTTP Response Splitting:
Continuous Monitoring: ThreatNG's constant monitoring capabilities can help detect new exposures and vulnerabilities that may arise due to changes in the application or its environment, potentially introducing new risks related to response splitting.
Reporting: The detailed reports generated by ThreatNG, particularly the technical and prioritized reports, can provide valuable insights into potential security weaknesses that could contribute to response-splitting vulnerabilities.
Collaboration and Management: ThreatNG's collaboration features enable security teams to work together to address identified risks and implement necessary changes to mitigate the potential for response splitting.
Intelligence Repositories: Leveraging ThreatNG's extensive intelligence repositories, including known vulnerabilities and dark web data, can provide context and inform decisions about mitigating risks associated with response splitting.
Examples:
Scenario: ThreatNG's Domain Intelligence module identifies an exposed API endpoint that accepts user input and reflects it in the HTTP response headers without proper validation.
Potential Risk: This could allow attackers to inject CRLF characters and manipulate the response, potentially leading to XSS or cache poisoning.
Mitigation: The organization can use ThreatNG's findings to prioritize implementing input validation and output encoding for the API endpoint.
Scenario: The Sensitive Code Exposure module discovers code snippets in a public repository demonstrating insecure user input handling when generating HTTP responses.
Potential Risk: This suggests a potential for response-splitting vulnerabilities in the application.
Mitigation: The organization can leverage ThreatNG's alert to review and remediate the insecure code, ensuring proper input validation and output encoding is implemented.
Scenario: ThreatNG's Search Engine Exploitation facility uncovers error messages that reveal sensitive information about the application's internal workings.
Potential Risk: This could indicate inadequate output encoding, making the application susceptible to response-splitting attacks.
Mitigation: The organization can use ThreatNG's findings to implement proper output encoding and error-handling mechanisms.
Complementary Solutions:
While ThreatNG can help identify potential risks related to HTTP response splitting, it's crucial to integrate it with other security tools and practices for comprehensive protection:
Dynamic Application Security Testing (DAST): DAST tools can actively scan web applications to identify response-splitting vulnerabilities by sending malicious input and analyzing the responses.
Web Application Firewalls (WAFs): WAFs can help detect and block HTTP response splitting attacks by inspecting traffic for malicious patterns and blocking requests containing CRLF characters in suspicious contexts.
Secure Coding Practices: Implementing secure coding practices and following secure development guidelines can help prevent response-splitting vulnerabilities from being introduced in the first place.
By combining ThreatNG's capabilities with complementary solutions and secure development practices, organizations can effectively mitigate the risks associated with HTTP response splitting and build more secure web applications.
