Penchuk Cyber Blog

  In April 2025, Adyen, a leading global payment platform, experienced a series of sophisticated Distributed Denial-of-Service (DDoS) attacks that disrupted services across Europe. The attacks, occurring in three waves throughout the evening of April 21st, targeted Adyen's European data centers, leading to significant transaction failures and delays for customers. ​ These incidents underscore a growing trend in cyber threats: brief, high-intensity DDoS attacks designed to overwhelm systems before traditional mitigation strategies can respond effectively. ​ The Evolving Nature of DDoS Attacks Historically, DDoS attacks were prolonged events, giving security teams time to react and implement countermeasures. However, recent data indicates a shift towards shorter, more intense attacks. Cloudflare's Q1 2025 DDoS Threat Report revealed that the company mitigated 20.5 million DDoS attacks in just the first quarter, nearly matching the total number for all of 2024.   These h...

A Combined Volumetric Attack utilizing SYN Flood , UDP Flood , and ICMP Flood vectors is a high-impact DDoS strategy that overwhelms a target’s network and infrastructure by exploiting different protocol layers simultaneously. This multi-pronged approach is designed to exhaust both bandwidth capacity and network stack resources , creating a sustained denial of service that is significantly harder to mitigate than single-vector attacks. The attack typically involves: SYN Floods targeting the TCP handshake process, depleting server connection tables and exhausting stateful resources. UDP Floods bombarding random or specific ports with massive amounts of connectionless datagrams, consuming bandwidth and CPU cycles. ICMP Floods (such as ping floods or smurf attacks) that generate excessive echo request packets to saturate network bandwidth and processing queues. By combining these vectors, attackers increase the entropy and complexity of traffic patterns, making it diffi...

A POST Flood Attack is a type of Distributed Denial of Service (DDoS) attack that targets the application layer (Layer 7 of the OSI model) by sending an overwhelming number of HTTP POST requests to a web server. Unlike traditional volumetric attacks that consume bandwidth, this method is designed to exhaust server resources such as CPU, memory, or application-specific processes. This form of attack is particularly insidious because it mimics legitimate traffic, making it difficult to detect using conventional anomaly detection systems or rate-limiting protections. Attack Methodology Connection Initiation : The attacker initiates multiple HTTP sessions, often via botnets or tools like LOIC, HOIC, or custom scripts. POST Request Flooding : Each session sends numerous HTTP POST requests with large payloads or incomplete data , often designed to keep the connection open for as long as possible. Server Exhaustion : Because POST requests typically require more server processing...

Class: Applicative Category: Layer 7 (Application Layer) DDoS Alternative Names: Slow HTTP POST, R-U-Dead-Yet (RUDY) A Slow POST attack is a type of application-layer DDoS attack that exploits the way web servers handle HTTP POST requests. Instead of overwhelming a server with a flood of requests, this attack operates by sending a legitimate-looking HTTP POST request with a declared large content length —but transmitting the actual body of the request extremely slowly , often byte by byte. The goal is to tie up server resources , keeping connections open for as long as possible. Since many web servers allocate memory and processing resources per open connection, a small number of Slow POST requests can exhaust available server threads or connection pools—leading to service degradation or complete unavailability. Attack Mechanism The attacker sends a valid HTTP POST request header with a large Content-Length value (e.g., Content-Length: 1000000 ). The body of the reques...

A Login Flood is a type of application-layer Denial of Service (DDoS) attack where an attacker sends a high volume of login requests to a target’s authentication endpoint. This is typically done to exhaust system resources, degrade performance, or cause total unavailability of the login service. Unlike brute force attacks that aim to gain unauthorized access, the goal of a login flood is disruption, not access. Attack Vector Login Flood attacks are usually executed via automated scripts or botnets that: Rapidly send repeated HTTP POST requests to the login endpoint (e.g., /login , /auth , /signin ) Include either random, valid, or dictionary-based usernames and passwords Often bypass simple rate-limiting by rotating IP addresses, user agents, or using proxy networks (e.g., TOR, VPNs) Impact Authentication Service Disruption : Legitimate users may experience slowdowns or inability to log in. Resource Exhaustion : CPU, memory, and database resources can be overwhelmed b...

 A TCP Connection Flood Attack is a type of Distributed Denial-of-Service (DDoS) attack that aims to overwhelm a target system by exploiting the TCP protocol’s connection-handling mechanisms. By inundating a server with a massive number of connection requests, the attacker consumes server resources, rendering the system unresponsive to legitimate traffic. How It Works The attack leverages the TCP three-way handshake process, which involves the following steps: SYN : The client sends a synchronization (SYN) packet to the server to initiate a connection. SYN-ACK : The server responds with a synchronization-acknowledgment (SYN-ACK) packet. ACK : The client sends an acknowledgment (ACK) packet back to the server, completing the handshake. There are two main flavours for this attack: Half-open connection in which the attacker sends a flood of SYN packets but deliberately does not complete the handshake by sending the final ACK. This leaves the server with numerous half-open...