CODEWITHSUNDEEP
asp.netcontent-security-policy
franzo
franzo

Reputation: 1469

Accessing Content Security Policy violation reports posted to ASP.Net

For example if you have a CSP like default-src 'self'; report-uri /CspViolationReport and if /CspViolationReport is handled by ASP.Net, how do you access the CSP violation report that is posted?

We expect to find some JSON posted, e.g. http://www.w3.org/TR/CSP11/#example-violation-report

When you inspect Request.Form, there are no keys, and there is no evidence of it in Request.ServerVariables["ALL_RAW"], but Request.ServerVariables["HTTP_METHOD"] is "POST".

Intercepting the POST with Fiddler, you can see that the JSON is certainly being posted, but .Net doesn't seem to let you see it.

Upvotes: 3

Views: 3833

Answers (3)

Tomasz Rzepecki
Tomasz Rzepecki

Reputation: 511

The problem might be with content-type of request: application/csp-report. It is not: application/json. I just added to WebApiConfig: 

config.Formatters.JsonFormatter.SupportedMediaTypes.Add(
new System.Net.Http.Headers.MediaTypeHeaderValue("application/csp-report"));

Of course you also need clases form other answers: CspReportContainer, CspReport

Upvotes: 7

Robin French
Robin French

Reputation: 715

Here's one using DataContractJsonSerializer which is in namespaces System.Runtime.Serialization and System.Runtime.Serialization.Json no other libraries required, it's all in the .NET Framework.

Controller:

public class ReportingController : Controller
{

    [HttpPost]
    public void CspReport()
    {
        var context = System.Web.HttpContext.Current;

        context.Response.ContentType = "application/json";
        context.Response.ContentEncoding = Encoding.UTF8;

        using (IO.Stream body = context.Request.InputStream) {
            var ser = new DataContractJsonSerializer(typeof(CspReportContainer));
            var report = (CspReportContainer)ser.ReadObject(body);
            ReportingControllerHelper.LogCspReport(report.Report);
        }
    }
}

Model:

[DataContract()]
public class CspReportContainer
{
    [DataMember(Name = "csp-report")]
    public CspReport Report { get; set; }
}
[DataContract()]
public class CspReport
{
    [DataMember(Name = "blocked-uri")]
    public string BlockedUri { get; set; }
    [DataMember(Name = "column-number")]
    public int? ColumnNumber { get; set; }
    [DataMember(Name = "document-uri")]
    public string DocumentUri { get; set; }
    [DataMember(Name = "effective-directive")]
    public string EffectiveDirective { get; set; }
    [DataMember(Name = "line-number")]
    public int? LineNumber { get; set; }
    [DataMember(Name = "original-policy")]
    public string OriginalPolicy { get; set; }
    [DataMember(Name = "referrer")]
    public string Referrer { get; set; }
    [DataMember(Name = "source-file")]
    public string SourceFile { get; set; }
    [DataMember(Name = "status-code")]
    public int? StatusCode { get; set; }
    [DataMember(Name = "violated-directive")]
    public string ViolatedDirective { get; set; }
}

Upvotes: 1

franzo
franzo

Reputation: 1469

Here's a way, inspired by http://muaz-khan.blogspot.co.nz/2012/06/exploring-csp-content-security-policy.html, thanks!

void ProcessCspValidationReport() {
    Request.InputStream.Position = 0;
    using (StreamReader inputStream = new StreamReader(Request.InputStream))
    {
        string s = inputStream.ReadToEnd();
        if (!string.IsNullOrWhiteSpace(s))
        {
            CspPost cspPost = JsonConvert.DeserializeObject<CspPost>(s);
            //now you can access properties of cspPost.CspReport
        }
    }
}

class CspPost
{
    [JsonProperty("csp-report")]
    public CspReport CspReport { get; set; }
}

class CspReport
{
    [JsonProperty("document-uri")]
    public string DocumentUri { get; set; }

    [JsonProperty("referrer")]
    public string Referrer { get; set; }

    [JsonProperty("effective-directive")]
    public string EffectiveDirective { get; set; }

    [JsonProperty("violated-directive")]
    public string ViolatedDirective { get; set; }

    [JsonProperty("original-policy")]
    public string OriginalPolicy { get; set; }

    [JsonProperty("blocked-uri")]
    public string BlockedUri { get; set; }

    [JsonProperty("source-file")]
    public string SourceFile { get; set; }

    [JsonProperty("line-number")]
    public int LineNumber { get; set; }

    [JsonProperty("column-number")]
    public int ColumnNumber { get; set; }

    [JsonProperty("status-code")]
    public string StatusCode { get; set; }
}

Upvotes: 6

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