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C#

C# static code analysis

Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C# code

  • All rules 493
  • Vulnerability46
  • Bug88
  • Security Hotspot24
  • Code Smell335

  • Quick Fix 61
 
Tags
    Impact
      Clean code attribute
        1. Using unsafe code blocks is security-sensitive

           Security Hotspot
        2. Not specifying a timeout for regular expressions is security-sensitive

           Security Hotspot
        3. Hard-coded secrets are security-sensitive

           Security Hotspot
        4. Constructing arguments of system commands from user input is security-sensitive

           Security Hotspot
        5. Deserializing objects without performing data validation is security-sensitive

           Security Hotspot
        6. Disabling ASP.NET "Request Validation" feature is security-sensitive

           Security Hotspot
        7. Allowing requests with excessive content length is security-sensitive

           Security Hotspot
        8. Using publicly writable directories is security-sensitive

           Security Hotspot
        9. Using clear-text protocols is security-sensitive

           Security Hotspot
        10. Having a permissive Cross-Origin Resource Sharing policy is security-sensitive

           Security Hotspot
        11. Expanding archive files without controlling resource consumption is security-sensitive

           Security Hotspot
        12. Configuring loggers is security-sensitive

           Security Hotspot
        13. Using weak hashing algorithms is security-sensitive

           Security Hotspot
        14. Delivering code in production with debug features activated is security-sensitive

           Security Hotspot
        15. Disabling CSRF protections is security-sensitive

           Security Hotspot
        16. Searching OS commands in PATH is security-sensitive

           Security Hotspot
        17. Creating cookies without the "HttpOnly" flag is security-sensitive

           Security Hotspot
        18. Setting loose file permissions is security-sensitive

           Security Hotspot
        19. Using non-standard cryptographic algorithms is security-sensitive

           Security Hotspot
        20. Using pseudorandom number generators (PRNGs) is security-sensitive

           Security Hotspot
        21. Creating cookies without the "secure" flag is security-sensitive

           Security Hotspot
        22. Formatting SQL queries is security-sensitive

           Security Hotspot
        23. Hard-coded credentials are security-sensitive

           Security Hotspot
        24. Using hardcoded IP addresses is security-sensitive

           Security Hotspot

        Deserializing objects without performing data validation is security-sensitive

        intentionality - complete
        security
        Security Hotspot
        • cwe

        Deserialization process extracts data from the serialized representation of an object and reconstruct it directly, without calling constructors. Thus, data validation implemented in constructors can be bypassed if serialized objects are controlled by an attacker.

        Ask Yourself Whether

        • The data validation implemented in constructors enforces a relevant security check.
        • Objects instantiated via deserialization don’t run the same security checks as the ones executed when objects are created through constructors.

        There is a risk if you answered yes to any of those questions.

        Recommended Secure Coding Practices

        • At the end of the deserialization process it is recommended to perform the same validation checks as the ones performed in constructors, especially when the serialized object can be controlled by an attacker.

        Sensitive Code Example

        When a serializable class doesn’t inherit from ISerializable or IDeserializationCallback types and has a constructor using its parameters in conditions:

        [Serializable]
        public class InternalUrl
        {
            private string url;
        
            public InternalUrl(string tmpUrl) // Sensitive
            {
               if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
               {
                  url= "http://localhost/default";
               }
               else
               {
                  url= tmpUrl;
               }
            }
        }
        

        When a class inherit from ISerializable type, has a regular constructor using its parameters in conditions, but doesn’t perform the same validation after deserialization:

        [Serializable]
        public class InternalUrl : ISerializable
        {
            private string url;
        
            public InternalUrl(string tmpUrl) // Sensitive
            {
                if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
                {
                    url= "http://localhost/default";
                }
                else
                {
                    url= tmpUrl;
                }
            }
        
            // special constructor used during deserialization
            protected InternalUrl(SerializationInfo info, StreamingContext context) // Sensitive
            {
               url= (string) info.GetValue("url", typeof(string));
               // the same validation as seen in the regular constructor is not performed
             }
        
            void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
            {
                info.AddValue("url", url);
            }
        }
        

        When a class inherit from IDeserializationCallback type, has a constructor using its parameters in conditions but the IDeserializationCallback.OnDeserialization method doesn’t perform any conditional checks:

        [Serializable]
        public class InternalUrl : IDeserializationCallback
        {
            private string url;
        
            public InternalUrl(string tmpUrl) // Sensitive
            {
                if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
                {
                    url= "http://localhost/default";
                }
                else
                {
                    url= tmpUrl;
                }
            }
        
            void IDeserializationCallback.OnDeserialization(object sender) // Sensitive
            {
               // the same validation as seen in the constructor is not performed
            }
        }
        

        Compliant Solution

        When using ISerializable type to control deserialization, perform the same checks inside regular constructors than in the special constructor SerializationInfo info, StreamingContext context used during deserialization:

        [Serializable]
        public class InternalUrl : ISerializable
        {
            private string url;
        
            public InternalUrl(string tmpUrl)
            {
                if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
                {
                    url= "http://localhost/default";
                }
                else
                {
                    url= tmpUrl;
                }
            }
        
            // special constructor used during deserialization
            protected InternalUrl(SerializationInfo info, StreamingContext context)
            {
               string tmpUrl= (string) info.GetValue("url", typeof(string));
        
               if(!tmpUrl.StartsWith("http://localhost/") { // Compliant
                  url= "http://localhost/default";
               }
               else {
                  url= tmpUrl;
               }
             }
        
            void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
            {
                info.AddValue("url", url);
            }
        }
        

        When using IDeserializationCallback type to control deserialization, perform the same checks inside regular constructors than after deserialization with IDeserializationCallback.OnDeserialization method:

        [Serializable]
        public class InternalUrl : IDeserializationCallback
        {
            private string url;
        
            public InternalUrl(string tmpUrl)
            {
               if(!tmpUrl.StartsWith("http://localhost/")) // there is some input validation
               {
                  url= "http://localhost/default";
               }
               else
               {
                  url= tmpUrl;
               }
            }
        
            void IDeserializationCallback.OnDeserialization(object sender) // Compliant
            {
                if(!url.StartsWith("http://localhost/"))
                {
                    url= "http://localhost/default";
                }
                else
                {
                }
            }
        }
        

        See

        • OWASP - Top 10 2021 Category A8 - Software and Data Integrity Failures
        • OWASP - Top 10 2017 Category A8 - Insecure Deserialization
        • docs.microsoft.com - security-and-serialization
        • CWE - CWE-502 - Deserialization of Untrusted Data
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