Wireless Network Security: How Hackers Crack Your Wi-Fi
Understanding Wireless Network Security Threats
Protecting your wireless network with WPA2 encryption and a robust passphrase is crucial. However, it’s equally important to understand the specific attacks you are defending against.
How Attackers Compromise Encrypted Wireless Networks
This article details the methods attackers employ to breach encrypted wireless networks. It is not intended as a guide for malicious activity, but rather to provide insight into potential vulnerabilities.
Our goal is to illuminate the techniques used by attackers, enabling you to better secure your own network.
Common Attack Vectors
- Brute-Force Attacks: Attackers systematically attempt numerous password combinations.
- Dictionary Attacks: Pre-compiled lists of common passwords and phrases are used in an attempt to gain access.
- Rainbow Table Attacks: Pre-computed tables are utilized to quickly crack passwords.
These attacks exploit weaknesses in the passphrase itself, rather than the encryption protocol. A strong, unique passphrase is therefore essential.
Beyond password cracking, attackers may also leverage vulnerabilities in wireless access points or client devices.
The Importance of Strong Passphrases
A lengthy and complex passphrase significantly increases the time and resources required for a successful attack. Strong passphrases should be at least 12 characters long and include a mix of uppercase and lowercase letters, numbers, and symbols.
Regularly updating your passphrase is also a recommended security practice.
Staying Informed About Wireless Security
Understanding the methods attackers use is the first step towards strengthening your wireless network security. By implementing robust security measures and staying informed about emerging threats, you can significantly reduce your risk of compromise.
Examining Unencrypted Network Vulnerabilities
Related: The Risks of Operating an Open, Passwordless Wi-Fi Network
We will begin by considering the most vulnerable network configuration: an open network lacking encryption. Connection to such a network, and subsequent internet access, is freely available to anyone without the need for a password. This presents a potential legal liability if illegal activities are conducted using your IP address.
Beyond this, a less apparent danger exists. Data transmitted over an unencrypted network travels in a readable format, known as plaintext. Individuals within wireless range can employ packet-capturing software to intercept this data.
This process involves activating a laptop’s Wi-Fi adapter to capture all wireless packets transmitted in the vicinity – often referred to as operating in “promiscuous mode.” The captured packets can then be analyzed to monitor online activity. While HTTPS connections remain secure, all HTTP traffic is exposed.
The practice of capturing Wi-Fi data sparked controversy when Google’s Street View vehicles engaged in it. Packets collected from open Wi-Fi networks contained potentially sensitive information. Anyone within range of your network possesses the capability to capture this data, reinforcing the importance of securing your Wi-Fi network with a password.
Locating Concealed Wireless Networks
Wireless networks can sometimes be configured to be hidden from plain view. However, specialized tools like Kismet are capable of detecting these networks by displaying their SSID (network name) as empty.
Exploiting Network Discovery
While seemingly secure, hiding your network isn't a robust security measure. Attackers can employ a technique involving "deauthentication" frames. These frames mimic a disconnection signal from the access point.
When a device receives a deauth frame, it will automatically attempt to reconnect to the network. During this reconnection process, the SSID is broadcast, allowing an attacker to capture it. Prolonged network monitoring will inevitably reveal a client's connection attempt and, consequently, the SSID.
The Illusion of Security
Hiding your wireless network doesn't enhance security; it can actually diminish it. Devices will continuously search for the hidden network, making them vulnerable.
A nearby attacker can exploit this constant searching by impersonating the hidden access point. This can trick your device into connecting to a malicious access point controlled by the attacker, compromising your security.
- Deauthentication frames: Signals that mimic a disconnection, forcing devices to reconnect and reveal the SSID.
- SSID broadcasting: The transmission of the network name during connection attempts.
Therefore, relying on hiding your wireless network as a security measure is ineffective and potentially detrimental.
MAC Address Spoofing: A Security Risk
When network traffic is monitored using analysis tools, the MAC address of each connected device is revealed. This information is present within the data packets being transmitted.
An attacker observing a connected device can identify its unique MAC address. Knowing this address allows them to potentially impersonate that device on the network.
How MAC Address Spoofing Works
The attacker alters the MAC address of their own wireless hardware to precisely match the legitimate device's MAC address. This is known as MAC address spoofing.
Subsequently, the attacker may disconnect the legitimate client, either by waiting for a natural disconnection or by actively forcing it off the network through a deauthentication attack.
With the client disconnected, the attacker’s device, now presenting the spoofed MAC address, can connect to the Wi-Fi network. The network will recognize the address as authorized.
Breaking WEP and WPA1 Encryption
Related: Distinguishing Between WEP, WPA, and WPA2 Wi-Fi Passwords
Currently, WPA2 represents the contemporary and secure standard for Wi-Fi encryption. However, vulnerabilities exist within the older WEP and WPA1 encryption methods. (WPA1 is frequently designated simply as "WPA," but we will specifically use WPA1 to differentiate it from the more secure WPA2).
The inherent design of these encryption protocols is susceptible to compromise. Sufficiently captured network traffic allows for analysis and decryption. An attacker, after observing an access point and collecting approximately one day’s worth of data, can employ specialized software to crack the WEP encryption.
WEP is considered quite insecure, and alternative methods exist to expedite the cracking process by manipulating the access point. While WPA1 offers improved security, it remains vulnerable to attack.
Addressing Vulnerabilities in Wi-Fi Protected Setup (WPS)
Related: The inherent insecurity of Wi-FI Protected Setup (WPS) and the recommendation to deactivate it.
Network security can be compromised through the exploitation of weaknesses within the Wi-Fi Protected Setup (WPS) protocol. WPS allows devices to connect to a router using an 8-digit PIN, circumventing the need to enter the full encryption passphrase.
The PIN verification process is conducted in stages. Initially, the router validates the first four digits of the PIN, providing feedback to the connecting device regarding their accuracy. Subsequently, the router assesses the final four digits, again communicating the result to the device.
Due to the limited number of possible four-digit combinations, a malicious actor can employ a "brute force" attack against WPS security. This involves systematically attempting each four-digit number until the router confirms a correct match.
Mitigating WPS Risks
Disabling WPS is a crucial step in bolstering your network's defenses. However, it's important to note that some router implementations may not fully deactivate WPS even when disabled through the web interface.
For optimal security, consider utilizing a router that lacks WPS support altogether. This eliminates the potential for exploitation through this particular vulnerability.
- Disable WPS: This is the primary defense against WPS-based attacks.
- Router Selection: Opt for routers without WPS functionality for enhanced security.
Protecting your network requires vigilance and proactive measures. Understanding and addressing WPS vulnerabilities is a key component of a robust security strategy.
Cracking WPA2 Passphrases Through Brute-Force Methods
Related: Understanding Brute-Force Attacks: The Inherent Vulnerability of Encryption
Contemporary WPA2 encryption is typically compromised via a brute-force attack, often implemented as a dictionary attack. An attacker will observe network traffic, intercepting the handshake packets generated during device connection to a wireless access point. This packet capture is frequently facilitated by disconnecting a currently connected device.
Following capture, the attacker initiates a brute-force attempt, systematically testing potential Wi-Fi passphrases to successfully replicate the handshake. For instance, if the passphrase is set to "password," it meets the WPA2 requirement of being between eight and sixty-three characters in length.
A computer will then utilize a dictionary file—a list of common and potential passphrases—and sequentially test each entry. Examples include attempts like "password," "letmein,1," or "opensesame." This methodology is commonly referred to as a "dictionary attack" due to its reliance on such a file.
It becomes readily apparent that frequently used or simplistic passwords, such as "password," can be cracked relatively quickly. Conversely, a more complex and lengthy passphrase, like ":]C/+[[ujA+S;n9BYq9z>T@J#5E=g}uwF5?B?Xyg," may take an impractically long time to guess. Therefore, employing a robust passphrase of adequate length is crucial for security.
Essential Resources for Security Analysis
For a detailed look at the instruments employed by malicious actors, obtaining and executing Kali Linux is recommended. Kali Linux represents the evolution of BackTrack, a platform that may already be familiar to some. It comes equipped with a comprehensive suite of pre-installed network-penetration utilities, including Aircrack-ng, Kismet, Wireshark, and Reaver.
Naturally, effective utilization of these tools necessitates a degree of expertise, or at least the ability to research their functionalities.
Geographical Considerations
It's important to remember that all of these techniques necessitate the attacker being within the network's transmission range. Individuals residing in sparsely populated areas face a comparatively lower risk profile.
Conversely, those living in densely populated environments, such as an apartment complex in New York City, may be surrounded by individuals seeking to exploit unsecured networks for unauthorized access.
Image source: Manuel Fernando Gutiérrez on Flickr