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Real Life Application DOS Attacks Ziv Gadot, Radware. Agenda. Short Introduction to DOS Attacks Real Life DOS Attacks Review Q & A. DOS Typology. DOS Typology (Cont). Sockstress. 20 RPS. ICMP Flood. Slowloris. SYN Flood. HTTP Floods. 100-500 K PPS. ReDoS. Numerous Packets
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Agenda Short Introduction to DOS Attacks Real Life DOS Attacks Review Q & A
DOS Typology (Cont) Sockstress 20 RPS ICMP Flood Slowloris SYN Flood HTTP Floods 100-500 K PPS ReDoS Numerous Packets Attacks Few Packets Attacks Application Level Design Weakness
Lecture Scope Multi Packet DOS Attacks Web Attacks • Real life Attacks (seen by us) • SYN Flood • 3-Way-Handshake Flood • Connection Saturation Attack • GET Slash Flood • Image Fetching • Caching Bypass • Web Reflection Attack • Blended Attacks • Slowloris • Sockstress • ReDoS • SIP Attacks • SMTP Attacks • DNS Attacks
Goals • Knowing the enemy (as it actually is) • Once an attack is fully identified and characterized it becomes much easier to mitigate
SYN Attack SYN SYN+ACK • Motivation • Simple yet effective • SRC IP is spoofed (Attacker’s IP is not compromised, difficult to block) • Botnets power challenges the capacity of existing protections • Characterization • From 1K PPS up to 1M PPS and more • Identification : TCP Flag Distribution
3-Way-Handshake Flood SYN SYN+ACK ACK FIN 27K PPS • Motivation • Evade SYN attack protections • Attacks different resource (application) • Characterization • 27K PPS • Identification • TCP Flag distribution • SRC IP is not spoofed
Slow Connection Saturation Flood SYN SYN+ACK ACK Keep alive Keep alive • Motivation • Exhaustion the number of maximum sessions of a system • Evade classic protections • Characterization • Very slow rate (of opening new connections) • Identification • Numerous on-going connections from an IP
GET Slash Flood • Motivation • Application level attack • Very simple • Characterization • Lower rate than L3-L4 attacks • 2K RPS • Identification • Increase in HTTP RPS • Increase in users or RPS-per-users • The “GET /” is very noticeable
Large Image/Data Fetching /images/large-image.jpg Large replay • Motivation • Small request generates large reply (and labor) • Characterization • Fetching a reach page which triggered the pulling of large data Identification Change in inbound/outbound traffic rate (L2 bps) Normal: 1:5 Attack 1:30
Caching Bypass GET …. HTTP/1.1 …. Cache-Control: no-store, must-revalidate …. Website • Motivation • Force all impact on web server Cache Cache • Characterization • Cache control directive to override • Identification • Appropriate ‘Cache Control’ values
Reflection Attack Attacker Website A Website B (Victim) HTTP GET
iframe, width=1, height=1 search.php
Blended Attacks UDP Flood (18.4 Mbps) • Motivation • “SHITAT MATSLIACH” • Mitigation systems don’t handle well several attacks at once • Characterization • Blended attacks • Identification • Hard to identify, requires careful analysis PSH+ACK Flood (14.6K PPS) SYN Flood (16K PPS)
Summary DOS attacks become more application oriented Attacker constantly raise the bar When handling a DOS attack its careful identification and characterization is a key to a successful mitigation