Using Wireshark for Vulnerability Assessment

Introduction 

In the dynamic field of cybersecurity, vulnerability assessment plays a crucial role in proactively identifying system weaknesses before they can be exploited by the attackers. Among the various tools used for this purpose, Wireshark is a standout—an open-source, powerful network protocol analyzer that enables security professionals to inspect network traffic and detect potential security vulnerabilities. In this blog, we explore how Wireshark can be used effectively in the process of vulnerability assessment, along with practical techniques and real-world considerations. 

Features of Wireshark  

Wireshark is a free and open-source network protocol analyzer used to capture and inspect data packets traveling across a network in real time. It helps network administrators, cybersecurity professionals and developers troubleshoot network issues, analyze traffic flows and detect suspicious activity with high granularity. Its key features include the following: 

• Live Packet Capture: Records data as it flows through a network interface. 

• Deep Packet Inspection: Examines the content of each packet at various protocol layers. 

• Protocol Support: Understands and decodes hundreds of network protocols (e.g., TCP, HTTP, DNS, SSL). 

• Filtering and search capabilities: Allows users to filter traffic using powerful display filters. 

• Live and Offline Analysis: Supports both real-time traffic analysis and offline review of saved packet capture files (.pcap). 

• Support for multiple Operating Systems: Runs on Windows, macOS and Linux. 

• Packet colourization and decoding: Represents packets indicated with different customizable colours for important packets which may need user attention.

Vulnerability assessment with Wireshark 

Although Wireshark is not a dedicated vulnerability scanner like Nessus or OpenVAS, it serves a vital complementary role in the vulnerability assessment process by providing deep insights into real-time network traffic. In essence, Wireshark enriches vulnerability assessment efforts by offering granular, real-time network visibility, helping security teams detect, analyse and respond to threats that might otherwise go unnoticed. Its capabilities enhance and support the findings of traditional scanners in several key ways such as: 

• Identifying Unencrypted Data: Wireshark allows analysts to monitor network traffic for plaintext data transmissions, such as unencrypted credentials, sensitive information or insecure protocols like HTTP or FTP, which can be exploited by attackers. 

• Revealing Misconfigured or Exposed Services: By inspecting traffic between hosts, Wireshark can uncover signs of improperly configured services, open ports or outdated protocols in use—potentially highlighting areas not covered by automated scans. 

• Detecting Anomalies and Suspicious Patterns: Analysts can use Wireshark to spot unusual traffic patterns, such as frequent failed login attempts, port scanning behaviour or unexpected external connections, which may indicate malicious activity or ongoing reconnaissance. 

• Supporting Manual Vulnerability Validation: After automated tools identify potential vulnerabilities, Wireshark helps validate these findings by providing raw packet-level data. This allows security professionals to verify exploitation attempts, understand exploit behaviour and confirm the presence of vulnerabilities. 

  
  

Use Cases :

Detecting Cleartext Protocol Usage 

Despite advancements in secure communication protocols, many legacy systems and poorly configured environments still rely on unencrypted protocols such as FTP, Telnet or HTTP. Wireshark can be instrumental in identifying when sensitive data such as login credentials, personal information or configuration details is transmitted in cleartext. This visibility enables security professionals to pinpoint and mitigate critical vulnerabilities stemming from insecure communication channels, helping to enforce the use of secure alternatives like SFTP, SSH and HTTPS. 

Analyzing Unauthorized or Rogue Services 

Wireshark enables detailed inspection of network traffic, making it possible to discover unauthorized or unexpected services running on the network. For example, the presence of traffic related to unapproved database systems, web servers or file-sharing applications can signal potential security risks or policy violations. Identifying and isolating these rogue services is essential for maintaining a secure and compliant IT environment. 

Detecting Reconnaissance Activities (Scanning and Probing) 

Before launching an attack, adversaries often perform reconnaissance to gather information about network hosts, open ports and running services. Wireshark helps detect these activities by capturing patterns consistent with port scans, ping sweeps or service enumeration, typically conducted using tools like Nmap or Masscan. By recognizing such patterns early, organizations can respond proactively to potential threats before actual exploitation occurs. 

Monitoring for ARP Spoofing and Man-in-the-Middle (MITM) Attacks 

In local area networks (LANs), attackers may use ARP spoofing or poisoning techniques to redirect traffic through their systems, enabling man-in-the-middle attacks. Wireshark can detect telltale signs of ARP spoofing, such as multiple IP addresses resolving to a single MAC address or frequent unsolicited ARP replies. Identifying these anomalies allows defenders to respond quickly, preventing data interception and integrity breaches. 

 Spotting Protocol Misconfigurations 

Misconfigured network protocols—such as SMB, NetBIOS or SNMP—can unintentionally expose sensitive information like system names, shares or internal IP addresses. Wireshark provides visibility into the data being exchanged via these protocols, making it easier to identify unsafe configurations, outdated protocol versions or excessive permissions. Addressing these issues reduces the attack surface and limits an attacker’s ability to gather valuable internal data. 

Using Wireshark effectively 

Maximizing the power of Wireshark requires not only understanding how to capture traffic but also how to efficiently analyze and manage the data collected. The following tips will help streamline the workflow and improve the accuracy of assessments: 

Apply Capture Filters Strategically 

To prevent overwhelming your system and to focus on the most relevant traffic, it is crucial to define capture filters before starting a packet capture. Capture filters (e.g., port 80 or host 192.168.1.10) limit what data is collected, reducing noise and improving performance, especially in high-traffic environments. Unlike display filters, capture filters determine what is recorded in the first place, making them ideal for targeted investigations. 

Use Display Filters for Deep Analysis 

Once data has been captured, display filters are essential for drilling down into specific traffic of interest. These filters (e.g., http, ip.addr == 10.0.2.3 or tcp.flags.syn == 1) allow you to isolate suspicious, abnormal or relevant traffic patterns quickly. With hundreds of supported protocols and filter fields, mastering display filters significantly enhances your analysis speed and precision. 

 Reconstruct Conversations with “Follow Stream” 

Wireshark’s “Follow TCP Stream” feature is invaluable for reconstructing entire communication sessions between two endpoints. This is particularly useful for analyzing application-layer data, such as web requests, file transfers or chat sessions. It allows analysts to view the full dialogue in a human-readable format, making it easier to understand the context and intent of the communication. 

 Use Colourization for Quick Visual Cues 

Wireshark supports customizable colour rules to highlight specific traffic types or patterns. For example, you can assign colours to TCP SYN packets, HTTP requests or ICMP traffic. This visual differentiation helps analysts quickly identify anomalies, prioritize their focus and detect patterns that might otherwise be overlooked in a sea of packets. 

Save and Annotate Captures 

Regularly save your capture files (.pcap) and consider adding annotations for future reference or collaboration. This practice ensures reproducibility, facilitates knowledge sharing among teams and supports incident documentation or compliance reporting. 

Keep Protocol Knowledge Up to Date 

To interpret traffic effectively, it is essential to maintain a solid understanding of common network protocols and how they behave. Knowing what “normal” looks like makes it easier to spot “abnormal” or malicious activity. 

Vulnerability Assessment Limitations of Wireshark 

While Wireshark is an indispensable tool for network traffic analysis, it has several limitations when used for vulnerability assessment. Understanding these constraints is essential to using Wireshark effectively and in the proper context. 

Not a Standalone Vulnerability Scanner 

Wireshark is not designed to perform automated vulnerability detection like tools such as Nessus, OpenVAS or Qualys. It does not actively scan systems for known vulnerabilities or maintain a database of CVEs. Instead, Wireshark is a passive traffic analyzer, meaning it relies on existing network activity rather than initiating probing or scans. As such, it is best used to complement traditional scanners rather than replace them. 

Inability to Analyze Encrypted Payloads 

One of Wireshark’s most significant limitations is that it cannot inspect encrypted traffic. Protocols like HTTPS, SSL/TLS, SSH and certain VPNs encrypt payload data, rendering it unreadable to Wireshark unless decryption keys or session secrets are available. This makes it challenging to detect threats or vulnerabilities that may be hidden within encrypted channels unless special configurations (like SSL decryption) are in place. 

Requires Manual Interpretation and Expertise 

Wireshark does not automatically flag malicious behavior or misconfigurations. It requires the user to manually interpret packet-level data, which demands a solid understanding of networking concepts, protocols and traffic behaviors. Without sufficient expertise, there is a risk of misinterpreting results or overlooking critical issues. 

Limited Host-Based Insight 

Wireshark focuses exclusively on network-level data and does not provide information about the internal state or vulnerabilities of individual host systems. For example, it cannot detect missing patches, outdated software, local file system issues or misconfigured permissions on a host. For a complete assessment, host-based scanners and agents are needed in conjunction with network analysis.

Performance and Scope Constraints 

In high-throughput environments or large networks, capturing and analyzing all traffic can be resource-intensive. Long capture sessions may generate massive amounts of data, which can overwhelm system resources and make analysis unwieldy without the use of filters or segmentation techniques. 

Conclusion 

In summary, while Wireshark is a powerful network diagnostics tool, it should be viewed as a supplementary component in a broader vulnerability assessment strategy that includes automated scanners, endpoint monitoring and proper system hardening practices. Its ability to expose insecure protocols, detect anomalous traffic and provide insight into network behaviour makes it a valuable part of any assessment toolkit. By integrating Wireshark with other security measures, organizations can significantly enhance their visibility into potential threats - and take timely action to mitigate them. 

How Sujosu Can Help 

We, at Sujosu Technology have strong expertise in Wireshark and are willing to offer significant value to other organizations by helping them enhance their network visibility, detect security issues early and improve their overall cybersecurity posture.

Our expertise in Wireshark includes Network Traffic Analysis Services, Security Audits and Vulnerability Support, Protocol-Level Troubleshooting, Incident Response Support, Compliance and Governance Consulting and much more. Please get in touch with us for exploring and availing a variety of services we have to offer using our Wireshark expertise.