Think You’re Secure? Penetration Testing Will Reveal Common Vulnerabilities

Cybersecurity risks are no longer a distant threat – they’re a daily reality for businesses of all sizes. As organizations expand their digital footprints through cloud services, remote access systems, and interconnected applications, the number of potential entry points for attackers grows exponentially.

A single oversight can lead to a significant data breach or operational disruption. For example, misconfigured email systems like Microsoft Direct Send can leave your infrastructure vulnerable to attacks originating from inside your own network.

To combat these risks, businesses must adopt proactive cybersecurity practices, with penetration testing serving as the vital component in identifying and mitigating threats before they’re exploited.

What is Penetration Testing?

Many cyberattacks aren’t the result of highly sophisticated methods, but rather the exploitation of common, well-known vulnerabilities. Penetration testing, simulated attacks designed to probe system defenses, offers a practical way to reveal these hidden risks before a bad actor can take advantage of them.

A penetration test provides a real-world assessment of an organization’s security posture, enabling leadership to make informed decisions and prioritize remediation based on actual risk exposure.

This kind of testing goes beyond simple vulnerability scans by simulating real-world tactics, techniques, and procedures attackers might use — a distinction that’s important to understand and is covered in our comparison of threat emulation versus penetration testing.

By taking this approach, penetration testing provides a real-world assessment of an organization’s security posture, enabling leadership to make informed decisions and prioritize remediation based on actual risk exposure.

For instance, penetration testers often rely on techniques involving network name resolution protocols like Multicast DNS (mDNS), Link-local Multicast Name Resolution (LLMNR), and NetBIOS-Name Services (NetBIOS-NS), which attackers can abuse to escalate privileges.

What are Common Vulnerabilities Revealed Through Penetration Testing?

Penetration tests often reveal recurring vulnerabilities that continue to present significant risks in today’s IT environments. Common examples include:

1. Weak Authentication Mechanisms

Inadequate authentication remains a key weakness in many organizations. Simple or reused passwords, lack of password complexity requirements, and absence of multi-factor authentication (MFA) create low-hanging fruit for attackers. Credential-based attacks, such as brute-force attempts or credential stuffing, succeed precisely because many systems fail to implement robust authentication controls.

2. Active Directory Certificate Services (AD CS) Misconfigurations

AD CS extends Active Directory by providing public key infrastructure (PKI) services, but misconfigurations can open serious attack vectors. Two notable escalation paths frequently identified during testing are:

• ESC1: When low-privileged users are permitted to request certificates for any principal (e.g., other users or computers), they can impersonate higher-privileged accounts – such as domain admins – by requesting a certificate with an alternate subject name.
• ESC8: When New Technology LAN Manager (NTLM) relay is possible to a Certificate Authority’s web enrollment interface, attackers can request certificates on behalf of targeted accounts – potentially leading to impersonation and privilege escalation.

Both vulnerabilities are particularly dangerous due to their stealth and the high level of access they can provide. Penetration testing often uncovers AD CS templates or enrollment permissions that enable these attack paths.

3. Misconfigured/Unsecure Systems

Configuration errors are another common issue uncovered in penetration tests. These errors can affect everything from firewalls to network shares and cloud platforms. For example, a firewall might allow unnecessary inbound traffic, or a network share with sensitive information could be publicly accessible due to incorrect access permissions. These missteps often go unnoticed during routine operations but create serious openings for attackers.

4. Lightweight Directory Access Protocol (LDAP) Signing Not Enforced

Lightweight Directory Access Protocol is commonly used in Microsoft environments for directory queries and authentication. When LDAP signing is not enforced, it allows communications between clients and domain controllers to occur in plaintext, making them susceptible to man-in-the-middle (MitM) attacks. An attacker can intercept or alter traffic, steal credentials, or escalate privileges.

5. Machine Account Quota Misconfiguration

In Active Directory (AD), the ‘MachineAccountQuota’ setting allows authenticated users to create new computer objects by default; up to 10 per user. While intended to support flexibility in managing domain-joined machines, attackers can abuse this default configuration to create rogue computer accounts. These accounts can then be used to obtain Kerberos tickets, potentially opening new doors for escalating privileges within the domain.

Beyond the Checklist: The Strategic Value of Penetration Testing

Proactive penetration testing is one of the most strategic investments an organization can make to safeguard its digital infrastructure. Unlike traditional security assessments or compliance checklists, penetration testing simulates real-world attack scenarios to uncover not just isolated vulnerabilities, but how those weaknesses can be chained together to compromise critical systems.

This is especially important when dealing with commonly overlooked issues like unsecured LDAP communication or misconfigured Active Directory Certificate Services. These are not theoretical risks – they are practical, exploitable gaps that threat actors actively look for. Routine monitoring tools and patch management solutions simply aren’t designed to detect these kinds of multi-layered threats.

Penetration testing fills that gap by adopting an attacker’s perspective, identifying both technical flaws and strategic blind spots. When performed proactively and on a regular basis, it allows organizations to address vulnerabilities before they’re exploited, reduce overall risk, and reinforce trust with clients, partners, and regulators. It’s not just about finding problems – it’s about gaining the insight needed to stay ahead of evolving threats and make more informed, resilient security decisions.

For organizations still weighing the merits of different security assessments, our detailed discussion on vulnerability scanning versus penetration testing provides clarity on when and why to use each approach.

Ready to Strengthen Trust with Real-World Testing?

Overall, penetration testing should be seen not as a one-time project, but as an ongoing and essential part of a comprehensive cybersecurity strategy. As business systems evolve and new technologies are introduced, the attack surface shifts. Regular testing helps identify emerging vulnerabilities early and confirms that existing security controls continue to perform as intended.

In addition to improving internal security, penetration testing can also help organizations meet regulatory requirements and customer expectations around data protection and risk management. It provides tangible evidence that security is being taken seriously and that proactive measures are in place.

DenSecure, our team of advanced cybersecurity experts, delivers targeted, real-world penetration testing tailored to your environment and risk profile. As your technical partner, we help you stay ahead of emerging threats, maintain compliance with evolving regulations, and strengthen trust with clients, partners, and stakeholders.

Connect with DenSecure to schedule a consultation and take a proactive step toward strengthening your cybersecurity posture.