Unvalidated Redirect and Forwards Users don’t check the address bar MVC authentication (pre-3.0) is vulnerable. Check the ReturnUrl parameter – http://weblogs.asp.net/jgalloway/archive/201 1/01/25/preventing-open-redirection-attacks- in-asp-net-mvc.aspx
Failure to restrict URI access Security by obscurity is useless Restrict via ASP.NET – no rolling your own! Integrated pipeline restricts everything Use [PrincipalPermission] to protect yourself IIS7 replaces file ACLs with a web.config based authorization list.
Insecure Cryptographic Storage Symmetric – same key Asymmetric – public/private keys Use safe algorithms – Hashing : SHA256 Symmetric: AES Asymmetric:CMS/PKCS#7 Encrypt then sign
Insecure Cryptographic Storage Use symmetric when – All systems are under your control – No need to identify who did the encryption Use asymmetric when – Talking/accepting from external systems – Non-repudiation on who encrypted/signed (X509) – All in memory – so no large plain tex! Combine the two for speed and security
Insecure Cryptographic Storage Do not reuse keys for different purposes Store keys outside the main database Use CryptGenRandom for random numbers Use & rotate salts Use unique IVs DAPI can provide a key store
Cross Site Request Forgery WebForms – Lock ViewState using ViewStateUserKey Needs a way to identify user Set in Page_Init – Use a CSRF token – http://anticsrf.codeplex.com MVC - in form [ValidateAntiForgeryToken] – on action method Encourage users to log out When is a postback not a postback?
Injection Flaws SQL – Use SQL parameters – Remove direct SQL table access – When building SQL strings within SPs parameterise those too! Xpath – Use XsltContext – http://mvpxml.codeplex.com/
Injection Flaws DECLARE @cmd= 'SELECT * FROM Customer WHERE FirstName LIKE @first OR LastName LIKE @last' EXEC @cmd, N'@first nvarchar(25), @last nvarchar(25)', @first, @last
Changes from 2007 Malicious File Execution Information Leakage / Improper Error Handling Security Misconfiguration Un-validated Redirects and Forwards
The OWASP Top Ten A1-Injection A2-Cross Site Scripting (XSS) A3-Broken Authentication and Session Management A4-Insecure Direct Object References A5-Cross Site Request Forgery (CSRF) A6-Security Misconfiguration A7-Insecure Cryptographic Storage A8-Failure to Restrict URL Access A9-Insufficient Transport Layer Protection A10-Unvalidated Redirects and Forwards
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