How Hackers Skillfully Bypass Program Allowlists with DLLs

In this article, we delve into a technique called "side loading" that enables hackers to evade program allowlists, specifically by utilizing malicious DLL (Dynamic Link Library) files. We explore the ways in which hackers take advantage of incorrect program allowlist configurations, allowing them to execute malicious code undetected. By demonstrating how to create and execute a custom DLL file to run arbitrary code on a Windows system, we aim to provide valuable insights into this cybersecurity concern.
Understanding the Vulnerability of Program Allowlists
Program allowlists serve as a security measure to specify which programs are permitted to run on a system. However, hackers can exploit misconfigurations or weaknesses in these allowlists to execute malicious actions. By identifying and exploiting these vulnerabilities, attackers can gain unauthorized access and compromise the security of a system.
Unveiling the "Side Loading" Technique
One technique that hackers employ to bypass program allowlists is known as "side loading." By leveraging legitimate DLL files, they can conceal their malicious activities within the context of authorized software. The technique involves substituting a trusted DLL with a malicious one, effectively fooling the system into executing the attacker's code.

Exploiting Incorrectly Configured Program Allowlists
DLL Hijacking and Malicious Intent
Hackers can take advantage of incorrectly configured program allowlists to perform DLL hijacking. This involves placing a malicious DLL file in a location where an authorized program expects to find a legitimate DLL. When the program attempts to load the DLL, it unwittingly executes the attacker's code, granting them control over the system.
Techniques for Creating Custom Malicious DLLs
Creating custom malicious DLLs allows hackers to evade detection by security mechanisms. They can use various methods, such as code injection or modifying existing DLLs, to embed their malicious code. By disguising their activities within legitimate software components, hackers can remain undetected for longer periods.

Executing Arbitrary Code Using a Custom DLL
Paragraph 5: Steps to Create and Execute a Custom DLLTo demonstrate the severity of this issue and raise awareness about the potential risks, we will outline the steps involved in creating and executing a custom DLL on a Windows system. Please note that this demonstration is for educational purposes only and should not be used for malicious intent.
Step 1 - Creating the Custom DLL
We start by creating a custom DLL using programming tools, such as C/C++ or other compatible languages. The DLL will contain the attacker's malicious code, which may include actions like capturing sensitive data, gaining unauthorized access, or initiating further attacks.
Step 2 - Replacing the Legitimate DLL
The next step involves substituting the legitimate DLL file with the custom malicious DLL. This can be achieved by placing the malicious DLL in the same directory or location where the authorized program expects to find the legitimate DLL.
Step 3 - Execution and Arbitrary Code
When the authorized program is launched, it unknowingly loads the malicious DLL, executing the attacker's code. This enables the hacker to carry out their intended actions, bypassing program allowlists and evading detection.

Mitigating DLL-Based Attacks
Strengthening Program Allowlists
To defend against DLL-based attacks, it is crucial to maintain robust program allowlists. Regularly review and update these lists to ensure they are accurate and up-to-date. Implementing strict allowlist policies and conducting periodic vulnerability assessments can significantly reduce the risk of DLL hijacking.
Monitoring and Detection
Implementing advanced security solutions that monitor and analyze system activity can help detect suspicious behavior associated with DLL-based attacks. Intrusion detection systems (IDS) and intrusion prevention systems (IPS) can provide real-time monitoring and alert administrators to any unauthorized DLL loading attempts or suspicious activities.
Patch Management and Software Updates
Keeping software and operating systems up to date is crucial in mitigating DLL-related vulnerabilities. Regularly applying patches and updates from software vendors helps address known vulnerabilities and strengthens the overall security posture of the system. By staying current with the latest security patches, organizations can reduce the risk of exploitation through DLL-based attacks.
Secure Development Practices
Developers play a critical role in preventing DLL-related vulnerabilities. Following secure coding practices and guidelines can significantly reduce the chances of creating DLLs that can be exploited. Conducting thorough code reviews, implementing input validation, and utilizing secure coding frameworks are essential steps in ensuring the integrity and security of DLL files.

Conclusion and Taking Action Against DLL-Based Attacks
Staying Vigilant and Educated
As cyber threats continue to evolve, it is crucial to stay informed and educated about the latest attack techniques. By understanding the intricacies of DLL-based attacks and the methods employed by hackers, individuals and organizations can take proactive steps to protect their systems and data.
Building a Strong Cybersecurity Culture
Creating a strong cybersecurity culture within an organization is paramount. This includes regular employee training on best practices, emphasizing the importance of following secure protocols, and fostering an environment where reporting suspicious activities is encouraged. By empowering employees with knowledge, organizations can collectively contribute to a more secure digital landscape.
Collaboration and Knowledge Sharing
Collaboration within the cybersecurity community is vital for staying one step ahead of hackers. Participating in forums, attending conferences, and sharing knowledge and experiences with peers help in identifying new threats and developing effective countermeasures. By working together, we can collectively improve cybersecurity practices and protect against DLL-based attacks.
In conclusion, understanding how hackers evade program allowlists with DLLs is crucial in strengthening our defenses against cyber threats. By exploring the side loading technique and demonstrating the creation and execution of custom DLLs, we shed light on the severity of this issue. By implementing robust program allowlists, monitoring system activity, practicing secure development, and fostering a cybersecurity culture, we can mitigate the risks posed by DLL-based attacks. Let us continue to stay vigilant, educated, and collaborative in our efforts to safeguard our systems and data from cybercriminals.