Certified: The Security+ Prepcast

Applications are the engine of modern digital life. From simple websites to complex cloud-native platforms, software powers communication, finance, education, and nearly every industry. But applications are also frequent targets for attackers. Vulnerabilities in application code can lead to data breaches, service outages, and unauthorized access. For security professionals, understanding how to protect applications—especially web-based ones—is essential. In this episode, we focus on key techniques to make applications more secure: input validation, secure cookie management, static code analysis, and code signing.
We begin with input validation. One of the most common ways attackers target applications is by submitting malicious input. This might involve special characters designed to trick the system into running unauthorized commands or accessing unintended resources. These kinds of attacks—such as Structured Query Language injection or command injection—are possible when the application does not properly verify and handle the input it receives from users. In other words, the application trusts input that it should not.
Input validation is the practice of carefully checking all data received from external sources before processing it. The goal is to make sure the input matches expected patterns and does not contain harmful content. For example, if a form asks for a zip code, it should only accept numeric values of a certain length. If the user enters letters, symbols, or extra-long strings, the system should reject the input. Validation can be done on the client side, such as in the browser, and on the server side, which is more reliable. Both methods help prevent attacks.
Rigorous input validation helps prevent a wide range of threats, including Structured Query Language injection, cross-site scripting, buffer overflows, and format string attacks. It is especially important to validate input that interacts with system functions, databases, or external services. In secure application development, input validation is considered a first line of defense. Developers should avoid using blacklists—where known bad input is blocked—and instead use whitelists, which define exactly what is allowed. This makes it harder for attackers to bypass filters using clever tricks.
Next, let’s talk about secure cookie management. Cookies are small pieces of data that websites store on a user’s device to remember things like login status, preferences, or tracking information. Because cookies are exchanged between the browser and the server, they can become targets for attacks if not secured properly. For example, an attacker might steal a cookie through a cross-site scripting attack and use it to impersonate the user.
To mitigate these risks, developers must apply security flags to cookies. One important flag is the Secure flag, which ensures that the cookie is only sent over encrypted connections like Hypertext Transfer Protocol Secure. Without this flag, the cookie could be transmitted over an unencrypted network and intercepted. Another key flag is HttpOnly. This prevents the cookie from being accessed by client-side scripts. If an attacker injects a malicious script into a webpage, the HttpOnly flag helps prevent that script from stealing the cookie.
The SameSite attribute is also crucial. This setting controls how cookies are sent with cross-site requests. For example, if a user is logged into one site and visits another, a malicious site might try to use the browser’s session cookie to perform actions on the first site. By setting SameSite to Strict or Lax, developers can limit this behavior and reduce the chance of cross-site request forgery attacks. Together, these cookie flags provide strong protections for web applications and help preserve user privacy.
Now let’s turn to the second half of this episode—static code analysis and code signing. Static code analysis refers to the process of examining source code before it is run, to find potential security flaws or coding errors. This analysis is performed without executing the program. Instead, tools scan the codebase and flag risky practices, such as improper input handling, use of weak cryptography, or insecure function calls. Static analysis helps developers catch problems early, before the application is deployed to production.
Using static code analysis as part of the software development lifecycle has many benefits. It helps enforce secure coding standards, provides automated checks across large codebases, and reduces the chance of human error. In large development teams, static analysis can ensure consistency and highlight risky changes before they are merged. Many organizations integrate static analysis tools into their build pipelines, so that every change is automatically reviewed for potential issues. These tools can also be tuned to match the specific needs of the project, reducing false positives and focusing on high-priority risks.
However, static analysis is not a replacement for other forms of testing. It does not detect runtime issues or logic errors that depend on specific inputs or conditions. Instead, it complements other practices such as dynamic testing, fuzzing, and manual code reviews. When used together, these tools form a comprehensive strategy for identifying and fixing security weaknesses before they can be exploited.
Now let’s discuss code signing. Code signing is a technique that uses cryptographic signatures to verify the origin and integrity of software. When a developer signs their code, they create a digital signature using a private key. Anyone who downloads or installs the code can verify the signature using the corresponding public key. This process proves that the code came from a trusted source and that it has not been altered or tampered with since it was signed.
In practical terms, code signing protects users from malicious software and ensures the authenticity of updates. For example, when you download a software update for your operating system, the update is signed by the vendor. Your device checks the signature before installing the update. If the signature is missing, invalid, or comes from an untrusted source, the update is rejected. This helps prevent attackers from distributing malware disguised as legitimate software.
Code signing is especially important in environments where software is distributed over the internet or installed on sensitive systems. Organizations may use internal code signing processes to secure custom applications, scripts, and automation tools. Signing these components ensures that only approved code is allowed to run and that any unauthorized changes are detected. In regulated industries such as healthcare or finance, code signing may be a compliance requirement, providing an audit trail and accountability for software releases.
Let’s take a real-world example. A developer writes a software patch to fix a vulnerability in a web application. Before releasing the patch, they perform static code analysis to check for any new flaws introduced by the change. Once the code passes review, it is compiled and signed with the organization’s digital certificate. The signature is included in the installation package, allowing customers to verify that the patch is authentic and unmodified. This end-to-end process demonstrates a commitment to secure development and responsible software maintenance.
To summarize, application security starts with the basics—validating input, securing cookies, scanning code for vulnerabilities, and verifying software integrity. Each of these steps targets a different part of the application lifecycle, from design and development to deployment and execution. By combining these practices, organizations can reduce the risk of attacks, protect user data, and build more trustworthy systems.
As you prepare for the Security Plus exam, expect to see questions that cover these topics. You might be asked to identify a benefit of static code analysis, choose the correct flag to protect a cookie, or explain how input validation prevents injection attacks. Be ready to recognize real-world scenarios and recommend the appropriate control. Focus on understanding both the purpose of each technique and how it is applied in the software development process.