Chargen DDoS Attack: What It Is and How to Protect Your Network

A Chargen DDoS attack is a type of Denial of Service (DoS) attack that exploits a vulnerability in the Chargen protocol, typically used for testing and debugging network devices. Although this attack is less commonly discussed compared to more sophisticated DDoS methods, it can still be highly disruptive and cause significant damage to the targeted systems.

In this article, we’ll dive into what a Chargen DDoS attack is, how it works, and the steps you can take to protect your network from being compromised by this type of attack.

What Is a Chargen DDoS Attack?

The Chargen (Character Generator Protocol) is an old protocol originally developed in the 1980s as a part of the Internet Engineering Task Force (IETF) RFC 864. Its purpose was to generate a stream of characters (usually text or binary data) for testing and debugging network connections.

However, due to its design, Chargen became an easy target for malicious exploitation. In a Chargen DDoS attack, cybercriminals take advantage of a misconfigured or unsecured Chargen service to amplify traffic and flood a target server or network with massive amounts of data.

How Does a Chargen DDoS Attack Work?

A Chargen DDoS attack typically follows these steps:

1. Exploitation of open Chargen ports: The attacker locates devices or servers that have the Chargen service enabled and are connected to the internet. These devices typically have the protocol running on port 19.
2. Reflection: The attacker sends a request to a Chargen service on an unsuspecting server, often using a spoofed IP address. The server then responds to the spoofed IP with a large volume of data.
3. Amplification: Chargen responses are usually much larger than the original request. For example, a small request of a few bytes can trigger a response of several hundred bytes. This amplification increases the total volume of traffic sent to the target network.
4. Flooding the Target: By spoofing the target’s IP address, the attacker redirects the amplified Chargen traffic to overwhelm the victim’s server or network. The victim is then flooded with a massive volume of data, making it difficult for legitimate traffic to get through.

Why Is a Chargen DDoS Attack Dangerous?

While a Chargen DDoS attack is generally less powerful than other types of DDoS attacks like SYN floods or HTTP floods, it can still have significant consequences, especially if the attacker leverages multiple vulnerable devices. Some risks associated with Chargen DDoS attacks include:

• Service disruption: The victim’s network or server may be rendered inaccessible due to the excessive traffic, leading to downtime.
• Network congestion: This type of attack can flood the target network with unnecessary data, causing legitimate traffic to be delayed or lost.
• Resource exhaustion: Attackers can exhaust the resources of the victim’s infrastructure, leading to a degradation of performance or complete failure of services.
• Amplification: Since the attacker can amplify the volume of traffic, a Chargen DDoS attack can be highly effective, even if the attacker has limited resources.

How to Protect Against a Chargen DDoS Attack

Given the potential risks of a Chargen DDoS attack, it’s essential to take the right steps to safeguard your network and mitigate the impact of such attacks. Here are some ways to protect against this threat:

1. Disable the Chargen Service

The most effective way to prevent a Chargen DDoS attack is to disable the Chargen service entirely, especially if it’s not necessary for your systems. In most modern systems, the Chargen service is obsolete and rarely needed.

• For Linux/Unix systems: Use the command sudo systemctl stop chargen to stop the service. You can also disable it from starting up automatically by running sudo systemctl disable chargen.
• For routers and firewalls: Many network devices, including routers and firewalls, have options to block or disable the Chargen protocol. Check your device’s settings to ensure it’s not running.

2. Block Port 19 (Chargen Port)

If disabling the service is not feasible, another preventive measure is to block incoming traffic on port 19, which is the default port for Chargen.

You can block port 19 on your network devices and firewalls to prevent any inbound Chargen requests, thereby stopping the amplification process.

• On firewalls: Set up rules to block traffic on port 19 and monitor for any suspicious inbound traffic.
• On routers: Many routers allow administrators to filter or block traffic based on specific ports. Set up rules to drop any packets that use port 19.

3. Implement Rate Limiting

Rate limiting is a technique used to control the amount of incoming traffic to your network. By implementing rate limiting, you can ensure that any traffic requests, including those from Chargen services, are limited to a reasonable level.

• Set up rate limiting on firewalls or web servers to block excessive or unusual traffic patterns.
• Work with your ISP or cloud provider to set limits on the number of packets that can be processed within a specific timeframe.

4. Deploy DDoS Mitigation Services

To protect against a variety of DDoS attacks, including Chargen DDoS attacks, consider using DDoS mitigation services. These services specialize in filtering out malicious traffic and can help prevent your network from being overwhelmed.

Some DDoS protection services include:

• Cloudflare: Offers DDoS protection and web traffic filtering.
• AWS Shield: Amazon Web Services provides DDoS mitigation for websites hosted on AWS.
• Akamai: Offers security solutions, including DDoS protection, for enterprise networks.

These services can help you mitigate the impact of a Chargen DDoS attack, even if it comes from a large botnet.

5. Monitor Network Traffic for Anomalies

Consistent network monitoring can help you detect unusual spikes in traffic or signs of an impending DDoS attack. Using specialized software, you can identify patterns associated with Chargen DDoS attacks and take proactive measures to mitigate them.

• Use tools like Wireshark to analyze packet traffic.
• Set up automated alerts to notify you when traffic patterns deviate from normal.

6. Keep Systems and Firewalls Updated

Ensure your network devices, operating systems, and firewalls are always up-to-date with the latest security patches. This can help you defend against known vulnerabilities that attackers might exploit, including those related to the Chargen service.

Conclusion: Defending Against a Chargen DDoS Attack

While Chargen DDoS attacks are less common than some other forms of DDoS attacks, they can still pose a threat to any network that has vulnerable devices or services running the Chargen protocol. By understanding the risks and implementing the right preventive measures—such as disabling the Chargen service, blocking port 19, and using DDoS protection services—you can significantly reduce the likelihood of becoming a target of a Chargen DDoS attack.

Be proactive in securing your network, and regularly monitor for vulnerabilities that may be exploited by cybercriminals. With the right tools and strategies in place, you can minimize the risk of such attacks and ensure your systems remain secure.