Wi-Fi Security Audit Using Termux

Modern wireless networks are a complex ecosystem where data security directly depends on the quality of equipment configuration and the encryption protocols used. Termux is a powerful terminal emulator for the Android operating system that provides users with access to the Linux command line without the need for root privileges. Many information security enthusiasts use this tool to analyze the state of their networks, test password strength, and identify configuration errors.

It is important to note that any actions aimed at disrupting the operation of other people's networks or intercepting traffic without the owner's permission are illegal. Denial of Service (DoS) Denial-of-service attacks can disrupt critical infrastructure and block legitimate users from accessing resources. This guide is purely educational: we'll cover the theoretical aspects of vulnerabilities, how protocols work, and how to protect your perimeter from such threats.

Using a smartphone with installed Termux turns your mobile device into a portable laboratory for security auditHowever, it's important to understand the limitations of mobile hardware. Standard Wi-Fi modules in phones often don't support monitoring mode (monitor mode) or packet injection, which is critical for deep traffic analysis. Therefore, we will focus on methods available for verifying configurations and security theory without requiring specialized equipment.

⚠️ Warning: Using tools to attack networks that you do not own or do not have written permission to test is punishable by law. All methods described below are only applicable to your own equipment or to legitimate cybersecurity competitions (CTFs).

Preparing the Termux environment for working with network utilities

The first step in setting up a lab setup is to properly install and configure the basic software. Termux provides a package repository similar to Linux distributions, allowing you to install the necessary compilers and libraries. To get started, you need to update your package lists and install a basic set of utilities, such as python, git And clang, which will be required to compile specialized software.

The installation process requires care, as some packages may take up significant space or require additional dependencies. Compilation Installing tools on a mobile device can take longer than on a desktop PC, so be patient. It's also important to ensure a stable internet connection during the installation process to avoid damaging package manager files.

Once you have a basic environment set up, you can begin cloning open source repositories. Many tools, such as Aircrack-ng (in adapted versions) or Reaver, require specific libraries for working with wireless interfaces. However, as mentioned earlier, without driver support for monitoring mode, functionality will be limited to logic-level analysis, not radio-physical analysis.

Theoretical Foundations of Wi-Fi Protocol Vulnerabilities

To understand how network disruption occurs, it is necessary to understand the architecture of wireless data exchange. The protocols of the family IEEE 802.11 Use various authentication and encryption mechanisms. The most common security standards are WPA2 and the newer WPA3. Vulnerabilities often lie not in the encryption algorithm itself, but in the protocol implementation or weak user passwords.

Attacks like Deauthentication (Deauthentication) is based on the fact that control frames in the Wi-Fi standard are often unencrypted, even if the data is transmitted encrypted. This allows an attacker to send a packet impersonating the access point to the client (or vice versa) demanding that the connection be terminated. The critical point is that the access point cannot distinguish a legitimate connection termination request from a fake one, since MAC addresses are easy to spoof.

Let's look at the main types of vulnerabilities that are exploited during an audit:

• 📡 Weakness of the handshake: Intercepting the connection process allows you to launch a brute-force attack offline.
• 🔓 WPS vulnerabilities: The Wi-Fi Protected Setup protocol has fundamental flaws in its PIN design, allowing it to be recovered in a matter of hours.
• 📉 Flooding attacks: Frame control channel congestion, resulting in reduced throughput or complete failure of service.

Why is WPS considered insecure?

The WPS protocol uses an 8-digit PIN. However, verification occurs in two stages: the first 4 digits and the second 4 digits are checked separately. This reduces the number of combinations from 100 million to approximately 11,000, making brute-forcing a trivial task for modern computing power.

Traffic analysis and target network search

The audit process begins with reconnaissance. It's necessary to scan the airwaves to detect available access points, determine their channels, encryption type, and the number of connected clients. Termux can use scanning utilities for this, although their effectiveness depends on the capabilities of the smartphone's Wi-Fi chip. The scan command typically returns a list of networks with their BSSID (MAC address of the access point) and the signal level (RSSI).

When analyzing the list of networks, pay attention to the following parameters:

• 📶 Signal level: The closer the RSSI value is to 0 (for example, -40 dBm), the stronger the signal and the more stable the connection.
• 🔐 Security type: The presence of WEP indicates a critical vulnerability, WPA2/WPA3 are the standard.
• 👥 Customer activity: The presence of connected devices makes the network potentially more vulnerable to social engineering or client software attacks.

The table below provides a comparison of the main security standards and their resistance to various types of attacks:

Mechanics of Denial of Service (DoS) attacks and their prevention

Availability attacks, often referred to as DoS (Denial of Service)In the context of Wi-Fi, attacks are aimed at making the network unavailable to legitimate users. The mechanism is usually simple: the attacker floods the channel with management frames or sends deauthentication packets continuously. This creates a "noise" that prevents devices from establishing a stable connection or forces them to disconnect repeatedly.

Technically, this is accomplished by creating a large number of virtual access points with the same SSID as the target network, or by continuously sending deauthentication frames. Termux When connected to the appropriate equipment, such packets can be generated. However, modern routers have protection mechanisms, such as ignoring unencrypted broadcast deauthentication requests (if the corresponding option is enabled in the 802.11w standard).

⚠️ Note: Router settings interfaces are constantly being updated. The location of menu items responsible for DoS attack protection (e.g., "Ignore Broadcast SSID" or "Protected Management Frames") may vary depending on the firmware (OpenWrt, DD-WRT, or the manufacturer's stock firmware). Always consult the official documentation for your device model.

To protect your own network from such influences, you must:

• 🛡️ Enable 802.11w (PMF): The Protected Management Frames protocol encrypts management frames, making it impossible to forge them without the encryption key.
• 📉 Power limit: Reducing the transmitter power reduces the range, making it difficult to carry out attacks from a distance.
• 👀 Log monitoring: Regularly check your router's system logs for multiple connection attempts or strange events.

Practical Application: Test Scenarios

Let's look at a scenario in which an administrator can test their network's resilience. Using Termux, you can run a scanning script that will show which devices can see your access point and at what signal strength. This helps identify "blind spots" or, conversely, areas where the signal extends far beyond the office or apartment, increasing the risk of interception.

Next, you can attempt to initiate a connection from the test device while monitoring the router logs. If the logs show mass deauthentication requests while you're running the test, the network is vulnerable to this type of attack (unless PMF is enabled). Audit It also includes password strength checking. Even if a brute-force attack on the network is impossible, a weak password can be brute-forced using a dictionary attack if an attacker intercepts the handshake hash.

The following commands are often used to perform tests (in the Linux/Android environment with the appropriate rights):

# Example command for scanning networks (requires an appropriate interface)
iwlist wlan0 scanning
Example of running an audit tool (hypothetical)
python audit_wifi.py --interface wlan0 --target AA:BB:CC:DD:EE:FF

Built-in smartphone modules often have limited driver functionality. For full-fledged testing, professionals use external USB Wi-Fi adapters with Atheros or Ralink chips, connected via OTG, which support the following modes: monitor And injection.

FAQ: Frequently Asked Questions about Wi-Fi Security

Is it possible to completely protect Wi-Fi from DoS attacks?

It's impossible to completely protect the physical layer (radio) from jamming or flooding attacks, as it's an open environment. However, the impact can be minimized by using protected management frames (802.11w) and intrusion detection systems (WIDS), which automatically block attackers' MAC addresses.

Do I need root to use Termux with Wi-Fi?

Root is not required for basic functions and file system access. However, for direct interaction with the Wi-Fi chip (switching to monitor mode, packet injection), superuser (root) privileges and special device driver support are required. Without root, functionality will be limited to TCP/IP-level network utilities.

What is a handshake and why are people afraid of it?

Handshake is the process of exchanging keys between the client and the access point upon connection. This process generates temporary encryption keys. If an attacker intercepts this exchange, they will obtain a hash that can be decrypted offline using brute-force attacks. Protection: Use long passwords (20+ characters) with a complex character set.

Is WPS dangerous if I don't use it?

Yes, it is dangerous if it's simply enabled in the router settings, even if you don't know the PIN. The protocol operates at the firmware level and may be enabled by default. It must be disabled in the wireless network settings, as the vulnerability lies in the authorization mechanism, not in the user's actual use.