Top 10 Security Vulnerabilities Found During Assessments
Introduction
Security vulnerabilities in applications and networks are a constant concern for organizations, as they can lead to data breaches, financial losses, and reputational damage. During security assessments, certain weaknesses appear repeatedly, exposing systems to attacks such as unauthorized access, data theft, and even full system compromise. This blog explores the top 10 security vulnerabilities most frequently identified during penetration tests and security audits.
From injection attacks that manipulate applications into executing malicious commands to weak passwords that provide an easy entry point for attackers, these risks highlight common oversights in security practices. Other frequent issues include unrestricted file uploads, which can allow malware distribution, and outdated software, leaving systems open to known exploits. Additionally, misconfigurations like unencrypted protocols and unnecessary exposed services expand the attack surface unnecessarily.
Understanding these vulnerabilities is the first step toward mitigating them. By recognizing where defenses often fail, organizations can prioritize fixes, implement stronger controls, and reduce exposure to cyber threats. Let’s examine these critical security gaps and how they can be addressed.
Injection Attacks
Injection attacks are among the most critical vulnerabilities found in web applications, allowing attackers to inject malicious code or commands. Common types include SQL injection, where attackers manipulate databases, and cross-site scripting (XSS), which hijacks user sessions. These attacks occur when applications fail to properly validate user input, enabling attackers to submit harmful data. Successful exploitation can lead to data theft, account compromise, or even full server control. To prevent injection flaws, developers must implement input validation, parameterized queries, and output encoding. Regular security testing helps detect such weaknesses before attackers exploit them. Ensuring secure coding practices is essential to defend against these high-risk threats.
Unrestricted File Uploads
Allowing users to upload files without proper restrictions is a major security risk often uncovered during assessments. Attackers can exploit this weakness by uploading malicious scripts, malware, or oversized files, leading to server compromise, data breaches, or denial-of-service (DoS) attacks. Common scenarios include attackers disguising harmful executables as innocent documents like resumes or profile pictures. To mitigate this risk, applications should validate file types, restrict upload sizes, scan for malware, and store files securely outside the web root. Implementing strict controls over file uploads prevents attackers from abusing this functionality while maintaining legitimate user convenience. Regular security audits help ensure these safeguards remain effective.
LLMNR/NBT-NS in Use
Many organizations unknowingly expose themselves to credential theft by keeping legacy name resolution protocols like LLMNR and NetBIOS Name Service (NBT-NS) enabled. While these protocols act as fallback mechanisms when DNS fails, they introduce serious security risks. Attackers can exploit them to perform man-in-the-middle (MitM) attacks, intercepting and poisoning name resolution requests to steal NTLMv2 password hashes. Once captured, these hashes can be cracked or relayed to gain unauthorized network access. Since modern networks rarely need these outdated protocols, disabling them significantly reduces attack opportunities while maintaining normal operations. Network administrators should prioritize disabling LLMNR/NBT-NS and enforcing stronger alternatives like DNS security extensions.
SMB Signing Not Enforced
A surprisingly common finding in internal network assessments is the failure to enforce SMB (Server Message Block) signing, a critical security feature that prevents credential relay attacks. While many organizations enable SMB signing, they often neglect to mandate its use across all systems. This oversight allows attackers to intercept and manipulate unencrypted SMB traffic, potentially gaining access to sensitive data or system controls.
The risks are particularly severe because SMB protocols frequently handle authentication traffic. Without enforced signing, attackers can exploit vulnerabilities to steal credentials, escalate privileges, or move laterally through a network. The solution is straightforward: organizations should configure Group Policy to require SMB signing for all client and server communications. This simple measure significantly hardens internal networks against one of the most prevalent attack vectors in enterprise environments.
Cleartext Protocols in Use
One of the most avoidable yet persistent vulnerabilities we encounter is the use of unencrypted communication protocols like HTTP, FTP, and Telnet. These outdated protocols transmit sensitive data—including login credentials and confidential information—as readable text across networks. During assessments, we frequently find them still active in both internal and external systems, often for legacy compatibility reasons.
The dangers are immediate: any attacker with network access can intercept communications, harvest credentials, or manipulate data without needing to break encryption. Modern alternatives like HTTPS, SFTP, and SSH provide robust encryption and should replace all cleartext protocols. Organizations must audit network services, disable obsolete protocols, and enforce encrypted communications to eliminate this unnecessary exposure. Regular scans help detect accidental reactivation of these risky services.
Insufficient Brute Force Protection
A surprisingly common oversight in security assessments is weak or missing defenses against brute force attacks. Many systems remain vulnerable because they fail to implement basic protections like account lockouts, login throttling, or multi-factor authentication (MFA). Attackers exploit this by running automated scripts that systematically guess passwords, often succeeding within hours when simple credentials are used.
The consequences can be severe—compromised user accounts, unauthorized data access, and potential network breaches. Effective protection requires layered security: enforcing strong password policies, implementing progressive delays after failed attempts, and mandatory MFA for sensitive systems. Regular monitoring for unusual login patterns provides additional detection capabilities. These straightforward measures dramatically reduce the risk of credential-based attacks while maintaining user accessibility.
Administrative/Unnecessary Services Exposed
Many organizations unknowingly expand their attack surface by leaving administrative interfaces and non-essential services exposed to the internet. During assessments, we commonly find RDP, SSH, database consoles, and web application admin panels unnecessarily accessible from external networks. These services become low-hanging fruit for attackers, who scan for them constantly.
The risks are severe: exposed services provide direct pathways for brute force attacks, vulnerability exploitation, and unauthorized access to sensitive systems. A single compromised administrative interface can lead to full network takeover. Best practices demand disabling internet-facing administrative access entirely, restricting services to internal networks or VPN-only connections, and implementing network segmentation. Regular port scanning helps identify and close accidental exposures before attackers discover them.
Default/Weak Passwords
Despite repeated warnings, default and weak passwords remain one of the most pervasive security issues uncovered during assessments. We routinely find unchanged factory credentials on network devices, IoT systems, and even critical infrastructure, along with easily guessable passwords like “Admin123” or “Password2023”. These vulnerabilities often stem from convenience over security or the false assumption that internal systems are safe from external threats.
The impact is severe: weak credentials serve as easy entry points for attackers, enabling them to bypass other security controls entirely. Once inside, attackers can move laterally, escalate privileges, or deploy malware. Organizations must enforce strong password policies, eliminate default credentials, and implement multi-factor authentication across all systems. Automated password auditing tools can help identify and remediate weak credentials before attackers exploit them.
SSL/TLS Configuration and Certificate Weaknesses
Security assessments frequently uncover encryption weaknesses in SSL/TLS implementations that leave communications vulnerable to interception. Common issues include outdated protocols (SSL 3.0, TLS 1.0/1.1), weak cipher suites, and improperly configured certificates like self-signed or expired credentials. These flaws often persist due to legacy system requirements or configuration oversights.
The consequences are serious: attackers can decrypt sensitive traffic, perform man-in-the-middle attacks, or impersonate legitimate services. Modern security standards require disabling vulnerable protocols, enforcing strong cipher suites, and maintaining valid certificates from trusted authorities. Regular scans and automated monitoring help ensure configurations remain secure as threats evolve. Proper implementation of TLS 1.2/1.3 with robust certificates is essential for protecting data in transit against increasingly sophisticated attacks.
Outdated/Unsupported Software
One of the most critical yet preventable vulnerabilities we encounter is organizations running obsolete software versions that vendors no longer patch. This includes end-of-life operating systems, unpatched server applications, and outdated web components like WordPress plugins or Java frameworks. Many systems remain vulnerable due to compatibility concerns or lack of patch management processes.
The risks are severe: attackers actively exploit known vulnerabilities in unsupported software to deploy malware, steal data, or gain system control. The 2017 WannaCry attack famously targeted unpatched Windows systems. Organizations must maintain a current software inventory, prioritize critical updates, and replace unsupported products with maintained alternatives. Automated patch management systems help ensure timely updates across all enterprise assets.
Additional Critical Vulnerabilities Worth Addressing
Beyond the top 10 vulnerabilities, security assessments frequently uncover several other concerning gaps that organizations should not ignore. Improper access controls routinely plague web applications, enabling unauthorized data access through vulnerabilities like insecure direct object references. Network infrastructure often reveals DNS spoofing risks and weak WiFi security that expose internal communications.
Equally troubling are discoveries of unprotected credentials stored in scripts, documents, and configuration files. Human vulnerabilities persist through social engineering threats and compromised credentials from third-party breaches. Perhaps most alarming is the prevalence of poor network segmentation, where flat architectures allow attackers unrestricted movement after initial access. While these issues may not top vulnerability lists, addressing them significantly enhances an organization’s overall security resilience against evolving threats.
Conclusion
The vulnerabilities highlighted in this blog represent the most common—and often most exploitable—weaknesses found during security assessments. While each poses unique risks, they share a common theme: many stem from basic security oversights rather than complex flaws. By prioritizing these critical areas—from patching systems to enforcing strong authentication—organizations can significantly reduce their attack surface. Regular security assessments and proactive mitigation are key to staying ahead of threats. Remember, robust cybersecurity isn’t about perfection but about addressing the most dangerous vulnerabilities before attackers can exploit them.