WiFi Security Audit: Checking Passwords in Kali Linux

In today's digital world, wireless networks have become an integral part of the infrastructure of any home or office, but they often become a point of entry for hackers. Using an operating system Kali Linux Penetration testing allows security administrators to identify weaknesses in router configurations before criminals can exploit them. Understanding how traffic is intercepted and decrypted is essential for building truly robust network perimeter security.

Password checking isn't just a matter of running a single command, but rather a complex algorithm of actions that involves preparing equipment, intercepting handshake messages, and using dictionary attacks. Ethical hacking This rule requires that all actions be performed exclusively on networks owned by you or where you have received written permission. Failure to comply may result in serious legal consequences and violation of data protection laws.

In this article, we'll take a detailed look at the technical aspects of working with wireless interfaces in Linux, examining WPA2-PSK encryption mechanisms and methods for analyzing them. You'll learn which tools are included in the standard distribution kit and how to correctly interpret wireless scanning results. A proper testing approach helps prevent data leaks and block unauthorized access to local resources.

Preparing the Kali Linux hardware and environment

The first and critical step is choosing a suitable wireless adapter that supports monitor mode and packet injection. Most cards built into laptops lack the necessary functionality, so security professionals use external USB devices based on chips. Atheros, Ralink or RealtekWithout support for these technologies, software-based handshake interception becomes impossible, as the card will filter unnecessary frames at the hardware level.

After connecting the adapter, you need to ensure that the operating system has identified it correctly. To do this, enter the following command in the terminal: iwconfig or more modern ip link, which displays the status of all network interfaces. If a device is visible but cannot enter the desired mode, additional drivers will need to be installed, which is often the most difficult part of setup for beginners.

It's important to understand that working with network interfaces requires superuser rights. All commands in Kali Linux Run as root, giving you full control over the hardware. Incorrect configuration may temporarily disable the adapter or require a system reboot to restore normal operation.

⚠️ Attention: When working with wireless card drivers in Linux, there is a risk of software bricking the device. Before installing third-party drivers, create a system restore point or backup important configuration files.

Monitor mode and packet injection

To analyze traffic passing through your card, you need to switch your network interface to monitor mode. In normal mode, the card connects to only one access point and ignores other frames, while monitor mode allows you to "hear" all radio channels in range. To activate this mode in Kali, use the utility airmon-ng, which automatically disables interfering processes and changes the interface state.

The switching process is as follows: first, the network manager is stopped, then a virtual interface is created. The command airmon-ng start wlan0 (where wlan0 is the name of your adapter) will create a new interface, usually called wlan0monAll future data capture tools will work with this new interface.

Packet injection is the ability of a card to not only receive but also send specially crafted frames into the network. This is necessary for deauthentication attacks, where a security administrator forcibly disconnects a legitimate client from the router. When the client reconnects, a key exchange occurs, which is recorded for subsequent analysis.

Not all adapters operate reliably in monitor mode at all frequencies. Some models may overheat or lose connection under heavy load, so selecting high-quality equipment is essential for successful testing. Driver stability directly impacts the quality of captured data.

Why do built-in maps often not work?

Many laptop manufacturers use chips with proprietary drivers or limited functionality that don't support the low-level operations required for security audits. Professional work requires specialized adapters with open-source drivers.

Scanning the airwaves and searching for targets

Once the interface has been successfully configured, the reconnaissance phase begins, the purpose of which is to detect target wireless networks. The tool airodump-ng is an industry standard for visualizing airspace, displaying the SSID, signal strength, channel, and encryption type. The operator should select a network with active clients, as their interaction with the access point is of interest.

When scanning, pay attention to the column #Data, which shows the number of captured data packets. A network where this counter is increasing indicates active information exchange, increasing the chances of successfully capturing a real-time handshake. Passive waiting can take a long time if users are inactive on the network.

Channel-based filtering allows you to focus on a specific frequency while ignoring noise from neighboring networks. The command to initiate a channel-based scan is airodump-ng --channel 6 wlan0monThis reduces the load on the processor and makes the information output more readable for the operator.

Visual analysis of the network list helps quickly weed out secure corporate networks with complex infrastructures and focus on home routers, which are often configured by default. However, even complex networks can have vulnerabilities in protocol implementation.

WPA/WPA2 Handshake Capture

The most crucial step in the audit process is capturing the four-way handshake, which occurs when the client connects to the network. It is at this point that password hashes are transmitted, which can then be decrypted. Without a captured handshake, further analysis is impossible, so this stage receives the utmost attention.

To force a connection to be broken in order to force a reconnection, a utility is used. aireplay-ng. Team aireplay-ng --deauth 10 -a [BSSID] wlan0mon sends deauthentication packets, forcing devices to reconnect. If there are active devices on the network, the handshake will be intercepted almost instantly, and in the corner of the screen airodump-ng a corresponding notification will appear.

In some cases, clients may not respond to deauthentication or quickly reconnect automatically, making interception more difficult. In such situations, specialists rely on methods to anticipate natural activity or employ more sophisticated techniques to attract the client's attention, such as creating fake access points with the same name.

⚠️ Attention: Sending deauthentication packets en masse can be considered a DoS (denial of service) attack. Use this feature only in a controlled lab environment or on your own equipment.

After successful capture, the file is saved to disk and can be checked for keys using the utility aircrack-ng or hashcatThe presence of a full handshake ensures that the data collection process has been completed successfully.

Brute-force and dictionary attacks

The resulting handshake file contains a hashed version of the password, which cannot be read directly. Offline attacks are used to recover the original text, the primary one being dictionary attack. This method involves sequentially hashing words from a large database (dictionary) and comparing the result with the captured hash.

The effectiveness of the attack directly depends on the quality of the dictionary used and the computing power of the hardware. Standard dictionaries, such as rockyou.txt, contain millions of popular passwords and allow you to quickly find weak keys set by users by default or based on simple words.

To speed up the process, graphic processing units (GPUs) and specialized software like Hashcat, which can try millions of combinations per second. There are also hybrid attacks that combine words from the dictionary with the addition of numbers or special characters, significantly expanding the range of variants checked.

If a password is complex and not found in any dictionary, a brute-force attack (trying all possible combinations) can take years. That's why password length and complexity are key defenses against such hacking methods.

Protecting your wireless network from hacking

Understanding attack methods allows you to formulate effective defense strategies. The first step is to abandon the use of outdated WEP and WPA encryption protocols, as they can be cracked in minutes, even on a mobile phone. The modern standard is WPA3, which implements brute-force protection and improves encryption on open networks.

Using complex passwords longer than 15 characters, including mixed-case letters, numbers, and special characters, makes dictionary attacks virtually useless. The time required to crack such a key exceeds the age of the universe with current computing power.

Additional measures include disabling the WPS function, which often contains vulnerabilities that allow PIN recovery and network access without knowing the master password. Hiding the SSID and using MAC address filtering are also recommended. While these measures aren't absolute protection, they do create an additional barrier to attack.

Regularly auditing your network using the tools described helps ensure the effectiveness of your security measures. Only a comprehensive approach ensures the confidentiality of transmitted data.

Is it possible to hack WiFi without a handshake?

Without capturing the handshake or exploiting vulnerabilities in WPS (Pixie Dust attack), recovering a WPA2 password is virtually impossible. The protocol is designed so that the key is not transmitted in cleartext, but is calculated based on shared parameters known only to the client and access point at the time of connection.

How long does it take to brute force a password?

The time depends on the password complexity and the hardware's performance. A simple six-digit password can be brute-forced in seconds, while a 12-character random-character password can take centuries to brute-force, even on a cluster of graphics cards.

Is it legal to use Kali Linux?

Using Kali Linux and its security auditing tools is completely legal. The only illegal activity is unauthorized access to other people's computer networks and data. Always obtain written permission from the owner before testing.

What should I do if the adapter doesn't see 5 GHz networks?

Not all adapters support the 5 GHz band. Make sure your equipment is dual-band and try manually setting the scanning channel using the command airodump-ng --channel 36 wlan0mon, as automatic scanning may skip some frequencies.