What is a Spoofed Session Flood Attack?
A spoofed session flood is a form of DDoS (Distributed Denial of Service) attack where an attacker overwhelms a system by creating fake sessions that mimic legitimate user interactions. By manipulating session data to look like valid communication, the attacker floods the system with these fake requests, consuming resources and potentially causing the application to become unresponsive or leading to unauthorized access.
This type of attack exploits weaknesses in session management and network traffic monitoring, making it difficult to detect and mitigate.
How Does a Spoofed Session Flood Attack Happen?
Cybercriminals employ various tactics to simulate legitimate TCP sessions, allowing them to evade detection by network protection tools. Here’s how these attacks typically happen:
Attackers can submit a fake SYN packet (used to initiate a TCP connection), followed by multiple ACK packets (which acknowledge the receipt of data), and at least one RST (reset) or FIN (connection termination) packet. By crafting these packets, they mimic a genuine TCP session, tricking security systems into believing the communication is legitimate.
This tactic involves exploiting asymmetric routing, where inbound and outbound traffic follow different paths. By sending fake SYN packets, followed by a flood of ACK packets, and concluding with FIN/RST packets, attackers take advantage of network security tools that analyse traffic in one direction only, allowing the spoofed sessions to go undetected.
Additionally, attackers may use bots or scripts to generate large numbers of session IDs, some of which may match or closely resemble legitimate session IDs, allowing them to create spoofed sessions.
To further complicate detection, the attack begins directly with the transmission of multiple ACK packets, bypassing the SYN stage altogether, followed by one or more FIN/RST packets. This approach reduces the rate of spoofed packet transmission, making the attack more difficult to detect than traditional flooding attacks, yet it effectively consumes system resources, leading to denial of service.
How to Detect Spoofed Session Attacks?
There are several indicators and methods that can help in detecting these types of attacks:
Anomalous Traffic Patterns:
A sudden spike in session creation, especially from unfamiliar or unexpected sources, may indicate a session spoofing attempt.
Performance Issues:
Unexplained slowdowns, increased latency, or frequent crashes could be signs of a session flood attack.
Suspicious Session Behaviour:
Look for patterns such as sessions being created with identical or similar user agents, IP addresses, or other characteristics. Sessions that are unusually long-lived or short-lived without normal user activity are also red flags.
Log Analysis:
Regularly review server logs for anomalies in session creation and management. Automated log analysis tools can help identify potential spoofed session attacks more efficiently.
How to Prevent Spoofed Session Attacks?
Preventing spoofed session attacks requires a combination of strong session management practices, robust security measures, and vigilant monitoring:
Implement Strong Session Management:
Implement strong session management by using secure and unpredictable session IDs, regenerating them after login, and setting proper timeouts with re-authentication for sensitive actions.
Use Encryption:
Ensure all communication between the user and server is encrypted using HTTPS, making it harder for attackers to intercept session IDs.
Rate Limiting and Throttling:
Restrict session creation from a single IP by limiting requests within a set time frame and using CAPTCHA or other challenges to verify the legitimacy of high-volume requests.
Regular Security Audits:
Conduct regular security assessments to identify and fix vulnerabilities that could be exploited in a spoofed session attack. Keep all software and security tools updated with the latest patches.
Deploy Web Application Firewalls (WAFs):
A WAF like AppTrana can help filter out malicious traffic and block IP addresses known to be associated with session spoofing attacks.
