Attack Surface Analysis for dotnet/efcore

Attack Surface: SQL Injection (via Raw SQL)

Attack Surface Area: SQL Injection (via Raw SQL)
- Description: Injection of malicious SQL code into database queries.
- EF Core Contribution: Provides FromSqlRaw and ExecuteSqlRaw methods that allow developers to execute raw SQL queries, bypassing the built-in parameterization of LINQ-to-Entities. This is a direct EF Core feature that creates the vulnerability.
- Example:
```
// Vulnerable code:
string userInput = Request.Query["username"]; // Untrusted input
var users = context.Users.FromSqlRaw($"SELECT * FROM Users WHERE Username = '{userInput}'").ToList();
```
  An attacker could provide '; DROP TABLE Users; -- as the username.
- Impact: Complete database compromise, data loss, data modification, data exfiltration, denial of service.
- Risk Severity: Critical
- Mitigation Strategies:
  - Developer: Always use parameterized queries, even with FromSqlRaw and ExecuteSqlRaw. Use FromSqlInterpolated and string interpolation only for values, never for table or column names. Implement strict input validation before passing data to any EF Core method. Conduct thorough code reviews, specifically focusing on any use of raw SQL.
  - User/Administrator: Ensure database user accounts have the least necessary privileges. Regularly back up the database.

Attack Surface Area: SQL Injection (via Dynamic LINQ)
- Description: Injection of malicious code through dynamically constructed LINQ queries or expression trees.
- EF Core Contribution: EF Core's LINQ provider translates LINQ expressions into SQL. If the structure of the LINQ query is dynamically built based on untrusted input, it can create an injection vulnerability. This is a direct consequence of how EF Core processes LINQ.
- Example: A scenario where a user can control the OrderBy clause, potentially injecting SQL.
```
//Potentially vulnerable if 'orderByField' comes directly from user input
string orderByField = Request.Query["sort"];
var users = context.Users.OrderBy(orderByField).ToList(); //Simplified
```
  If orderByField is Username; WAITFOR DELAY '0:0:10'; --.
- Impact: Database compromise, data loss, data modification, data exfiltration, denial of service.
- Risk Severity: High
- Mitigation Strategies:
  - Developer: Avoid dynamic query construction based on untrusted input whenever possible. If unavoidable, use a whitelist approach. Consider a safe query builder library. Thorough input validation is essential.
  - User/Administrator: Similar to raw SQL injection mitigation.

Attack Surface Area: Data Exposure (Sensitive Data in Exceptions)
- Description: Exposure of sensitive information (connection strings, query fragments) in exception messages.
- EF Core Contribution: EF Core exceptions can, by default, include details that might be considered sensitive. This is a direct behavior of EF Core's exception handling.
- Example: A database connection error including the connection string in the exception message.
- Impact: Exposure of sensitive database credentials or query details.
- Risk Severity: High
- Mitigation Strategies:
  - Developer: Implement robust error handling and logging. Never expose raw exception details to the user. Sanitize exception messages. Use EnableSensitiveDataLogging(false) in production (and ideally in development).
  - User/Administrator: Ensure proper logging configuration.

Attack Surface Area: Denial of Service (Unbounded Queries)
- Description: Queries that return a large number of results, consuming excessive resources.
- EF Core Contribution: EF Core doesn't automatically limit the number of results returned by a query. This is a direct consequence of how EF Core handles query execution.
- Example:
```
// Returns all users.
var allUsers = context.Users.ToList();
```
- Impact: Server resource exhaustion, denial of service.
- Risk Severity: High
- Mitigation Strategies:
  - Developer: Always implement pagination (Skip and Take). Set reasonable limits.
  - User/Administrator: Monitor server resource usage.

Attack Surface Area: Data Tampering (Lack of Model Validation) - While EF Core doesn't directly cause this, it's highly relevant because EF Core is the data access layer.
- Description: Insertion of invalid or malicious data due to missing validation.
- EF Core Contribution: EF Core focuses on persistence; it doesn't inherently enforce business rules. It's the developer's responsibility to validate data before using EF Core to save it.
- Example: Saving a User with an invalid email or negative age.
- Impact: Data corruption, application instability, potential security vulnerabilities.
- Risk Severity: High
- Mitigation Strategies:
  - Developer: Implement comprehensive data validation before calling SaveChanges. Use data annotations, fluent validation, or custom logic.
  - User/Administrator: No direct mitigation.

Attack Surface Area: Data Tampering (Mass Assignment) - Similar to above, EF Core's update mechanism makes this relevant.
- Description: Unauthorized modification of entity properties.
- EF Core Contribution: EF Core allows updating by modifying properties and calling SaveChanges. If property access isn't controlled, this is a risk.
- Example: An attacker modifying the IsAdmin property.
- Impact: Unauthorized data modification, privilege escalation.
- Risk Severity: High
- Mitigation Strategies:
  - Developer: Avoid directly binding user input to entity objects. Use DTOs or view models, and explicitly control which properties are updated. Use a whitelist approach.
  - User/Administrator: No direct mitigation.