Top 5 cyber threats uncovered by penetration testing

Penetration testing, often referred to as a pen test, is a proactive approach to identifying vulnerabilities within an organisation’s IT infrastructure. 

By simulating real-world attacks, penetration tests reveal potential weaknesses that malicious actors could exploit. For businesses in the UK, where cyber crime is on the rise, penetration testing is a critical step towards strengthening cyber security. 

In this blog, we draw on insights from a detailed analysis conducted by the Infosec Institute to highlight the top five cyber threats commonly uncovered during penetration testing, and provide insight into how organisations can address these risks.

1. Misconfigured systems

Penetration tests frequently uncover systems that are improperly configured, leaving them exposed to exploitation. Examples include open ports, default credentials, and unpatched software.

Why it matters:

• Misconfigurations create entry points for attackers to infiltrate networks.
• Unpatched software can be exploited using publicly available vulnerabilities.

Server security misconfigurations are the most common vulnerability, accounting for 28.1% of findings in penetration tests. (Infosec Institute)

Mitigation tips:

• Conduct regular audits of system configurations and close unnecessary ports to prevent unauthorised access.
• Implement automated tools to identify and flag misconfigurations in real time.
• Change default credentials immediately upon setup to remove easily exploitable entry points.
• Patch and update software promptly to address known vulnerabilities and minimise the risk of exploitation.
• Enable logging and monitoring to detect and respond to potential misconfigurations quickly.

Read about secure configuration practices.

2. Vulnerable web applications

Web applications are a prime target for attackers, as they often expose critical functionality to external users. Common issues include SQL injection, cross-site scripting (XSS), and insecure APIs.

Why it matters:

• Exploiting web application vulnerabilities can result in data theft, website defacement, or service downtime.
• APIs that lack proper authentication and validation can become gateways for attackers.

Cross-Site Scripting (XSS) and Broken Access Control are among the most prevalent vulnerabilities, accounting for 15.5% and 14.7% of findings in penetration tests respectively. (Infosec Institute)

Mitigation tips:

• Use web application firewalls (WAFs) to detect and block malicious traffic in real-time, protecting against common attacks like SQL injection.
• Perform regular code reviews and vulnerability scans for applications to identify and fix weaknesses before attackers can exploit them.
• Implement secure coding practices, such as input validation and output encoding, to reduce the likelihood of vulnerabilities like cross-site scripting (XSS).
• Follow OWASP guidelines to secure web applications and APIs, ensuring proper authentication, session management, and data protection.
• Continuously monitor and log application activity to detect unusual behaviour indicative of an attack.

Explore OWASP’s top 10 vulnerabilities.

3. Phishing susceptibility

Penetration testing often includes simulated phishing attacks, which reveal how susceptible employees are to social engineering techniques. Phishing remains one of the most effective ways for attackers to steal credentials and distribute malware.

Why it matters:

• Phishing attacks are a leading cause of ransomware infections and credential theft.
• Even one single successful phishing attempt can compromise an entire network.

Mitigation tips:

• Use advanced email filtering solutions with AI-powered threat detection to block phishing messages and identify malicious attachments.
• Conduct regular phishing simulations to test employee awareness and provide targeted training based on results.
• Implement an organisation-wide policy requiring staff to verify unexpected requests for sensitive information or payments.
• Encourage a “report-first” culture, where employees alert IT teams to suspicious emails immediately, without fear of repercussions.
• Use domain-based authentication protocols such as DMARC, DKIM, and SPF to prevent email spoofing.

Understand phishing and how to prevent it.

4. Insider threats

Penetration tests often highlight the risks posed by insider threats, whether intentional or accidental. Employees or contractors with excessive access rights can unintentionally expose sensitive information or deliberately misuse their access.

Why it matters:

• Insider threats account for a significant percentage of data breaches.
• Excessive access rights can lead to privilege escalation by attackers.

A 2024 report revealed a 28% increase in insider-driven security incidents since 2021, indicating a growing concern for organisations.

Mitigation tips:

• Implement the principle of least privilege (PoLP) to ensure employees only have access to the systems and data necessary for their roles.
• Use role-based access control (RBAC) to assign permissions and reduce the risk of excessive access rights.
• Conduct regular access reviews to ensure permissions remain appropriate as roles and responsibilities change.
• Provide ongoing cyber security awareness training to employees, focusing on recognising and mitigating insider threats.
• Deploy monitoring tools to track unusual activity patterns and flag potential insider threats for investigation.

Learn how to manage insider risks.

5. Weak passwords

One of the most common vulnerabilities uncovered during penetration tests is staff using weak or easily guessable passwords. Attackers use brute force or dictionary attacks to exploit this weakness, gaining unauthorised access to systems. A lack of enforcement around strong password policies can exacerbate this issue.

Why it matters:

• Weak passwords expose sensitive systems, customer data, and intellectual property.
• A single compromised account can lead to a chain of data breaches.

A study by Cobalt revealed that issues related to authentication, including weak passwords, constituted 8% of the most common vulnerabilities found during penetration tests. (Infosec Institute)

Mitigation tips:

Policy-based solutions:

• Implement a strong password policy requiring at least 12 characters, including a mix of uppercase, lowercase, numbers, and special characters.
• Mandate regular password changes and enforce password history to prevent reuse of old passwords.
• Educate employees about the risks of using easily guessable passwords or sharing credentials.

Technical solutions:

• Enforce multi-factor authentication (MFA) to provide an extra layer of security beyond just passwords.
• Use enterprise-grade password management tools to generate, store, and share secure passwords safely.
• Implement account lockout mechanisms to block access after a set number of failed login attempts.
• Integrate with services that monitor for compromised credentials on the dark web to proactively alert administrators.
• Use biometric authentication where feasible to reduce reliance on passwords altogether.

Learn more about password policies and MFA.

Why penetration testing matters for UK businesses

Penetration testing provides businesses with invaluable insights into their security posture. By identifying and addressing vulnerabilities before attackers exploit them, organisations can reduce the risk of data breaches, service disruptions, and financial loss. In an era of rising cyber threats, regular pen tests are not just a best practice but a necessity for any organisation serious about cyber security.

How Securious can help with penetration testing

At Securious, we understand the unique challenges businesses face when it comes to securing their systems. That’s why we offer comprehensive, expert-led penetration testing services designed to:

1. Identify real-world risks

Our penetration testing team uses industry-leading methodologies to simulate real-world attack scenarios, uncovering vulnerabilities that could otherwise remain hidden.

2. Provide actionable insights

We deliver clear, actionable reports that go beyond technical jargon, helping your organisation to implement effective security measures.

3. Tailored solutions

Every organisation is unique, so we customise our approach to address your specific needs, whether you require network penetration testing, web application assessments, or phishing simulations.

4. Support compliance

Penetration testing can be important for meeting compliance standards such as ISO 27001 and PCI DSS. Our team ensures your testing aligns with these frameworks while enhancing your overall security.

5. Ongoing support

We don’t stop at testing. Our experts work with you to prioritise the remediation of identified risks, making recommendations for how you should secure your systems.

Contact us today to learn how our penetration testing services can strengthen your security.