What is a DDoS Attack?
A distributed denial-of-service (DDoS) attack is a malicious attempt to disrupt normal traffic of a targeted server, service or network by overwhelming the target or its surrounding infrastructure with a flood of Internet traffic (source: https://www.cloudflare.com/learning/ddos/what-is-a-ddos-attack/).
In a DDoS attack, the incoming traffic flooding the victim originates from many different sources – potentially hundreds of thousands or more. This effectively makes it impossible to stop the attack simply by blocking a single source. These flood attacks are often generated by botnets – networks of compromised computers, routers, and internet-connected devices (source: https://www.fortinet.com/resources/cyberglossary/ddos-attack).
The main impact of DDoS attacks is the denial of service – making a website or other internet service slow or unavailable to its intended users. This can cause lost revenue due to downtime and recovery costs for the victim. DDoS attacks can also consume bandwidth, overload firewalls, and occupy resources needed for legitimate requests (source: https://www.cloudflare.com/learning/ddos/what-is-a-ddos-attack/).
IP Address of Attacker
While a DDoS attack may appear to originate from a single IP address or range, the attacker’s true IP address can be hidden using various techniques:
IP spoofing involves altering packet header information to make the attack seem to come from a different address. The attacker can forge fake source IP addresses, making it difficult to pinpoint their location (Source).
Proxy servers act as an intermediary for traffic between the attacker and victim. The proxy IP address obscures the attacker’s real address. Multiple proxy layers provide greater anonymity (Source).
Attackers avoid detection through botnets – networks of compromised devices that launch attacks in a distributed manner. Tracking down each bot participating is infeasible (Source).
Packet Analysis
One of the main ways to trace a DDoS attack is through deep packet analysis. This involves capturing packets sent during the attack and analyzing their contents to gather information about the attacker (Detection of DDoS attack via deep packet analysis in real time systems, https://www.researchgate.net/publication/320829304_Detection_of_DDoS_attack_via_deep_packet_analysis_in_real_time_systems).
By looking at the packet contents, investigators can extract details like the IP address of the attacker. However, this IP address is usually spoofed. More useful information can be gleaned by analyzing packet timestamps, sizes, and order to identify patterns and digital fingerprints unique to the attacker (How to Trace DDOS Attack through Wireshark Utility, https://www.youtube.com/watch?v=k1RU4uwapi8).
Investigators can also examine packet routes to geolocate the attacker. Packets will often travel through the attacker’s true geographic location even if the IP is spoofed. By finding common geographic intersections in packet routes, the physical source of the attack can be narrowed down (Detection of DDoS attack via deep packet analysis in real time systems, http://ieeexplore.ieee.org/document/8093526/).
In summary, deep packet analysis allows investigators to uncover digital fingerprints and geolocation clues that may help trace DDoS attacks back to their source.
ISP Cooperation
Internet service providers (ISPs) play a critical role in tracing DDoS attacks back to their source. When a DDoS attack is detected, the victim’s ISP can start collaborating with other ISPs to analyze traffic and identify the original source IP addresses of the attack (Source: https://www.netscout.com/blog/ddos-mitigation-collaboration).
By sharing network and traffic data, multiple ISPs can trace the attack traffic step-by-step through various network hops until they reach the originating network. This tracing process relies on cooperation between ISPs to share necessary data. However, legal obstacles sometimes prevent ISPs from fully disclosing traffic logs and details to other networks (Source: https://www.darkreading.com/perimeter/how-to-trace-a-ddos-attack).
Victims of DDoS attacks should inform their ISP as soon as an attack is detected. The sooner the collaborative tracing process starts, the better chance there is of tracking down the real source before the attack ends. But full cooperation between ISPs across legal jurisdictions is not always guaranteed.
Honeypots
Network security administrators can set up honeypots to study DDoS attacks and gather information about attackers. Honeypots are decoy systems that appear vulnerable but actually monitor and log all activity. When attackers target a honeypot, administrators can analyze the traffic to identify the sources and methods used in the attack. As Johannes Krupp from the RIPE Network Coordination Centre explains, “The SISSDEN project (sissden.eu) operates a network of honeypots designed to detect these attacks, observing 10,000 per day.” [1] By closely analyzing honeypot logs using packet capture tools, forensic investigators can extract details about the botnets, software tools, and network infrastructure used in DDoS attacks.
Honeypots allow network defenders to gather valuable intelligence about attackers that can be used to identify them and aid in legal prosecutions. As Mikołaj Nawrocki et al. explain, honeypots are “designed to detect incoming attacks” and “collect data to facilitate attribution.” [2] While attackers can use technical means like VPNs or Tor to mask their identities, honeypots provide additional clues that may reveal origins when thoroughly analyzed. However, ethical and legal considerations apply when studying attacker behavior to avoid entrapment or overreach.
Log Analysis
Looking at web server logs is one of the most effective ways to trace a DDoS attack. By analyzing access logs, error logs and other log files, you can identify patterns that indicate an attack is occurring. Some signs to look for in logs include:
Sudden spikes in traffic coming from a single IP address or block of IP addresses. This could point to a botnet flooding the server with requests.[1]
High volumes of requests for the same resource or page. Attackers will repeatedly request the same assets to overload the server.[2]
Increased errors related to overloaded resources like database connection failures or timeouts. This indicates the attack is successfully exhausting backend resources.[3]
Using log analysis tools to visualize traffic and detect anomalies can quickly alert to potential DDoS attacks in real-time. By pinpointing suspicious patterns, you can gather evidence to trace the attack back to its source.
[1] https://www.loggly.com/blog/how-to-detect-and-analyze-ddos-attacks-using-log-analysis/
[2] https://www.tek-tools.com/apm/detect-ddos-attack-with-log-analysis
[3] https://www.chaossearch.io/blog/how-to-mitigate-ddos-attacks
Forensic Analysis
Forensic analysis involves digging into captured traffic and log data to reconstruct the timeline of a DDoS attack. By analyzing large amounts of network traffic, forensic investigators can identify patterns that reveal how the attack unfolded (Forensic Analysis of a DDoS Attack, https://www.linkedin.com/pulse/forensic-analysis-ddos-attack-darragh-delaney). Traffic is captured at various points across the network and then reconstructed to determine the sources and nature of the attack traffic. This allows investigators to pinpoint the botnets, methods, and tools used in the DDoS campaign.
Forensic analysis relies heavily on log data from routers, firewalls, intrusion detection systems, and other network devices. Logs provide detailed information on traffic volumes, protocols, ports, access times, and more. By correlating log data with packet captures, investigators can recreate the sequence of events leading up to and during the attack. The goal is to identify patient zero – the initial compromised device that sparked the botnet attack. Understanding the full anatomy of the attack is key to mitigating and defending against future strikes.
Legal Action
Law enforcement agencies like the FBI investigate DDoS attacks as cybercrimes that can lead to arrest and criminal prosecution (FBI). The Department of Justice has charged perpetrators of DDoS attacks under the Computer Fraud and Abuse Act, which can lead to significant prison sentences and financial penalties (DOJ).
Working with law enforcement on DDoS attacks can be challenging due to the technical sophistication required to trace attacks across the internet. Investigators may need to obtain warrants and subpoenas to access logs from internet service providers in order to follow the attack path back to the perpetrator (UpGuard). Prosecution can also be difficult if attacks originate from abroad or utilize compromised botnets.
However, cooperation between international law enforcement agencies has led to successful prosecutions. DDoS services and botnets are being systematically dismantled through takedown operations. Though legal action remains complex, it demonstrates these attacks are serious crimes with real consequences.
Mitigation Techniques
There are various ways to minimize the impact of DDoS attacks on networks and infrastructure. According to Cloudflare, traffic scrubbing is one of the most effective mitigation techniques. Scrubbing centers inspect incoming traffic and filter out bad traffic before it reaches the target server. This protects the server from overload and service disruption. Cloudflare operates large-scale scrubbing centers across the globe to soak up DDoS attacks.
Additional mitigation tactics include:
- Blackhole routing – routers block and discard traffic sent to the target IP address (https://blogs.blackberry.com/en/2022/11/ddos-attack-8-simple-prevention-and-mitigation-strategies)
- Rate limiting – restrict the number of requests allowed from an IP address
- Web application firewalls – inspect and filter incoming HTTP requests
No single solution can fully prevent DDoS attacks. A layered security approach using multiple techniques gives the best protection. With vigilance and proactive measures, organizations can minimize the risk and impact of DDoS attacks on their infrastructure.