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Symmetric denial of service

Description​

The server is rendered unresponsive by successively repeating a request which consumes a lot of resources or takes too long to be processed.

Impact​

Deny temporary or permanently the access to one or several application services.

Recommendation​

Define a time-out when a query or a search is taking a lot of time processing the information

Threat​

Anonymous attacker from the Internet.

Expected Remediation Time​

⌚ 60 minutes.

Score​

Default score using CVSS 3.1. It may change depending on the context of the vulnerability.

Base​

  • Attack vector: N
  • Attack complexity: L
  • Privileges required: N
  • User interaction: N
  • Scope: U
  • Confidentiality: N
  • Integrity: N
  • Availability: H

Temporal​

  • Exploit code madurity: X
  • Remediation level: X
  • Report confidence: X

Result​

  • Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:X/RL:X/RC:X
  • Score:
    • Base: 7.5
    • Temporal: 7.5
  • Severity:
    • Base: High
    • Temporal: High

Code Examples​

Compliant code​

If a very large query needs to be used, include a time-out limit to avoid crashing the server

public class QueryTimeout {
  public static void main(String[] args) {
    try {
      Statement stmt = connection.createStatement();
      //Set a query timeout limit
      stmt.setQueryTimeout(60);

      // Execute sql query
      ResultSet rs = stmt.executeQuery("select * from products");

      while (rs.next()) {
        System.out.println("code: " + rs.getString("code")
                + " ,product: " + rs.getString("name")
                + " ,price: " + rs.getDouble("price"));
      }
    } catch (SQLException e) {
        //Code to handle exception
    }
  }
}

Non compliant code​

The application contains queries that retrieve possible large amounts of information without any limits

public class QueryTimeout {
  public static void main(String[] args) {
    Statement stmt = connection.createStatement();

    // Execute sql query
    ResultSet rs = stmt.executeQuery("select * from products");

    while (rs.next()) {
      System.out.println("code: " + rs.getString("code")
              + " ,product: " + rs.getString("name")
              + " ,price: " + rs.getDouble("price"));
    }
  }
}

Requirements​

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