Description
Refit is an automatic type-safe REST library for .NET Core, Xamarin and .NET The various header-related Refit attributes (Header, HeaderCollection and Authorize) are vulnerable to CRLF injection. The way HTTP headers are added to a request is via the `HttpHeaders.TryAddWithoutValidation` method. This method does not check for CRLF characters in the header value. This means that any headers added to a refit request are vulnerable to CRLF-injection. In general, CRLF-injection into a HTTP header (when using HTTP/1.1) means that one can inject additional HTTP headers or smuggle whole HTTP requests. If an application using the Refit library passes a user-controllable value through to a header, then that application becomes vulnerable to CRLF-injection. This is not necessarily a security issue for a command line application like the one above, but if such code were present in a web application then it becomes vulnerable to request splitting (as shown in the PoC) and thus Server Side Request Forgery. Strictly speaking this is a potential vulnerability in applications using Refit and not in Refit itself. This issue has been addressed in release versions 7.2.22 and 8.0.0 and all users are advised to upgrade. There are no known workarounds for this vulnerability.
EPSS Score:
0%
Comprehensive Technical Analysis of EUVD-2024-3184
1. Vulnerability Assessment and Severity Evaluation
Vulnerability Description:
The vulnerability in the Refit library, specifically in its handling of HTTP headers, allows for CRLF (Carriage Return Line Feed) injection. This occurs because the HttpHeaders.TryAddWithoutValidation method does not validate for CRLF characters in header values. This can lead to the injection of additional HTTP headers or the smuggling of entire HTTP requests.
Severity Evaluation:
The vulnerability has a CVSS (Common Vulnerability Scoring System) base score of 10.0, which is the highest possible score, indicating a critical severity. The vector string CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H indicates:
- Attack Vector (AV): Network
- Attack Complexity (AC): Low
- Privileges Required (PR): None
- User Interaction (UI): None
- Scope (S): Changed
- Confidentiality (C), Integrity (I), Availability (A): High impact on all three
2. Potential Attack Vectors and Exploitation Methods
Attack Vectors:
- Request Splitting: An attacker can inject CRLF characters to split the HTTP request, allowing them to inject additional headers or even entire HTTP requests.
- Server Side Request Forgery (SSRF): By manipulating the headers, an attacker can trick the server into making unauthorized requests to internal or external services.
Exploitation Methods:
- Header Injection: An attacker can inject malicious headers by exploiting the lack of validation in the
HttpHeaders.TryAddWithoutValidationmethod. - Request Smuggling: By injecting CRLF characters, an attacker can smuggle additional HTTP requests, potentially bypassing security controls.
3. Affected Systems and Software Versions
Affected Software:
- Refit library versions prior to 7.2.22 and 8.0.0.
Affected Systems:
- Any application using the vulnerable versions of the Refit library, particularly web applications where user-controllable values are passed through to headers.
4. Recommended Mitigation Strategies
Immediate Actions:
- Upgrade: Upgrade to Refit versions 7.2.22 or 8.0.0, which have addressed the vulnerability.
- Input Validation: Ensure that all user inputs are properly validated and sanitized before being used in HTTP headers.
Long-Term Strategies:
- Code Review: Conduct thorough code reviews to identify and mitigate similar vulnerabilities.
- Security Training: Educate developers on secure coding practices, particularly around handling user inputs and HTTP headers.
- Regular Updates: Implement a regular update and patch management process to ensure that all dependencies are up-to-date.
5. Impact on European Cybersecurity Landscape
Potential Impact:
- Widespread Adoption: Given the widespread use of .NET Core and Xamarin in European enterprises, this vulnerability could have significant implications if exploited.
- Data Breaches: The high impact on confidentiality, integrity, and availability could lead to data breaches, unauthorized access, and service disruptions.
- Compliance Risks: Organizations may face compliance risks under regulations such as GDPR if sensitive data is compromised.
Mitigation:
- Collaboration: Encourage collaboration between security researchers, vendors, and organizations to quickly identify and mitigate such vulnerabilities.
- Awareness: Raise awareness among developers and security professionals about the importance of secure coding practices and regular updates.
6. Technical Details for Security Professionals
Vulnerability Details:
- Vulnerable Method:
HttpHeaders.TryAddWithoutValidation - Impact: Allows CRLF injection, leading to request splitting and SSRF.
Proof of Concept (PoC):
- A PoC demonstrating request splitting can be found in the references provided.
References:
Conclusion: This vulnerability highlights the importance of input validation and secure coding practices. Organizations should prioritize upgrading to the patched versions of Refit and implement robust security measures to mitigate similar risks in the future.