DDoS Attack Mitigation: What Avi Vantage Protects Against

Avi Vantage is the last line of defense for most applications. In most deployments, Avi Vantage is directly exposed to public, untrusted networks. To protect application traffic, Service Engines (SEs) are able to detect and mitigate a wide range of Layer 4-7 network attacks. The following is a list of common denial of service (DoS) attacks and directed DoS (DDoS) attacks mitigated by Avi Vantage.

 

Attack Layer Attack Name Description Mitigation
Layer 3 SMURF ICMP packets with the dest IP set as the broadcast IP and the source IP spoofed to the victim’s IP Packets are dropped at the dispatcher layer if the source or destination IP is a broadcast IP or class D/E IP address.
ICMP flood Excessive ICMP echo requests to the victim ICMP packets are rate limited.
Unknown protocol Packets with unrecognized IP protocol Packets are dropped at the dispatcher layer.
Tear drop Exploit the reassembly of fragmented IP packets Packets are dropped in the protocol stack in the SE if fragment offsets are deemed bad.
IP fragmentation Bad fragmented packets Packets are dropped in the protocol stack in the SE.
Layer 4 SYN flood Send TCP SYNs without acknowledging SYN acks; the victim’s TCP table will grow rapidly If the TCP table is being filled with half connections (uncompleted TCP 3-way handshakes), begin using SYN cookies.
LAND Same as SYN flood except the source and dest IP addresses are identical Packets are dropped at the dispatcher layer,
Port scan TCP/UDP packets on various ports to find out listening ports for next level of attacks; most of those ports are non-listening ports Packets are dropped at the dispatcher layer.
X-mas tree TCP packets with all the flags set to various values to overwhelm the victim’s TCP stack Packets are dropped in the protocol stack of the SE.
Bad RST flood Send TCP RST packets with bad sequence Packets are dropped in the protocol stack in the SE if the packet sequence numbers are outside the TCP window.
Fake session Guess a TCP sequence numbers to hijack connections To reduce the chance of success for a fake session attack, the SE uses random numbers for the initial sequence numbers.
Bad sequence numbers TCP packets with bad sequence numbers Packets with sequence numbers outside the TCP window are dropped in the protocol stack in the SE.
Malformed/Unexpected flood Unrelated TCP packets after a TCP FIN has been sent Unexpected packets after the FIN are dropped in the protocol stack in the SE.
Zero/small window Attacker advertises a zero or very small window (<100) after the TCP 3-way handshake If the first TCP packet from the client (after a SYN) is received with a zero or small window, the SE drops the packet and a RST is sent.
Rate limiting CPS per IP Connection flood The rate limits configured in the application profile are applied. (App Profile - DDoS - Rate Limit HTTP TCP)
SSL errors Inject SSL handshake errors SE closes the connection after an error.
SSL renegotiation Request for renegotiation after establishing an SSL connection Client-triggered renegotiation is disabled.
Layer 7 (HTTP) Request idle timeout Establishing a connection without sending an HTTP request The control timeout configured in the application profile is used. (App Profile - DDoS - Post Accept Timeout)
Size limit for header and request Resource consumption via long request time The header-size limits configured in the application profile are used. (App Profile - DDoS - HTTP Size)
Slow POST Resource consumption via long request time The body-size limits configured in the application profile are used. (App Profile - DDoS - HTTP Size)
SlowLoris / SlowPost Opening multiple connections to the victim by sending partial HTTP requests The header and body timeouts configured in the application profile are used.
Invalid requests Invalid header, body, or entity in HTTP request The URI length, header length, and body length limits configured in the application profile are used.
Rate limiting RPS per client IP Request flood The limit configured in the application profile is used. (App Profile - DDoS - Rate Limit HTTP TCP)

Rate limiting RPS per URL Request flood The limit configured in the application profile is used. (App Profile - DDoS - Rate Limit HTTP TCP)

 

 

Updated: 2017-09-20 06:30:59 +0000