CCNA Explorer 4 Network Security

Sikkerhed

Security Terms

White hat

An individual who looks for vulnerabilities in systems or networks and then reports these vulnerabilities to the owners of the system so that they can be fixed.

Black hat

Another term for individuals who use their knowledge of computer systems to break into systems or networks that they are not authorized to use.

Hacker

A general term that has historically been used to describe a computer programming expert. More recently, this term is often used in a negative way to describe an individual that attempts to gain unauthorized access to network resources with malicious intent.

Cracker

A more accurate term to describe someone who tries to gain unauthorized access to network resources.

Phreaker

An individual who manipulates the phone network to cause it to perform a function that is not allowed.

Spammer

An individual who sends large quantities of unsolicited e-mail messages.

Phisher

Uses e-mail or other means to trick others into providing sensitive information.

Hacker Checklist

1. Performe footprint analysis also called reconnaissance
   1. Find responsive IP addresses
2. Enumerate information
   1. Collect more information about servers/network and version numbers
3. Manipulate users to gain access
   1. Test common known usernames and passwords
   2. Find out how the company chooses usernames and default passwords
4. Escalete privileges
5. Gather additional usernames, password and secrets
6. Install backdoors
7. Levage the compomised system
   1. Attack other systems

Network Security Policies

ISO 27002 define some guidelines for developing organizational security standards through the following 12 sections:

• Risk assessment
• Security policy
• Organization of information security
• Asset management
• Human resources security
• Physical and environmental security
• Communications and operations management
• Access control
• Information systems acquisition, development, and maintenance
• Information security incident management
• Business continuity management
• Compliance

See RFC 2196, Site Security Handbook

Security Weaknesses

There are three primary vulnerabilities or weaknesses:

• Technological weaknesses
  • TCP/IP protocol weakness
    • Syn flood
    • Unsecure protocols
  • OS Weakness
    • All operating systems have weaknesses
    • Is documented in CERT archives at www.cert.org
  • Network Equipment weakness
    • Routing protocols
    • Firewall holes
    • Lack of authentication
• Configuration weaknesses
  • Unsecure user accounts
  • Weak password
  • Misconfigures internet services
  • Default configuration
• Security policy weaknesses
  • Lack of written security policy
  • Lack of authentication continuity
  • Missing change management
  • Missing disaster recovery plan
• Physical security
  • Access Threats
    • Unlocked doors to equipment
  • Temperature Control
  • Electrical
    • No surge protection
    • Missing UPS
  • Maintenance threats
    • Poor maintenance of critical components
    • Lack of spare parts
    • Poor cabling
    • Poor labeling

Security Threats

Threats to network

• Social engineering
  • Phishing
  • Niagara letters
  • Fake Helpdesk calls to users
• Reconnaissance
  • Internet Queries
  • Ping sweeps
  • PortScans
  • Packet sniffers
• Access
  • Password Attacks
    • Easy passwords
    • Dictionary
    • Brute-force
  • Trust Exploitation
    • JumpHosts
  • Port redirection
  • MITM
• Denial of Service
  • DoS
  • Ping of Death
  • SYN Flood
  • DDoS
    • Smurf Attack
    • Tribe flood network(TFN)
    • Stacheldraht
    • MyDoom
• Worms, Viruses, and Trojan Horses
  • Worms
    • The enabling vulnerability
    • Propagation mechanism
    • Payload
  • Virus
  • Trojan Horses

Mittegation Techniques

• Host mittegation
  • Update OS
  • Install firewall
  • Install antivirus
  • Shutdown unnecessary services
• Network Mittegation
  • IPS
  • IDS
  • NAC
  • ASA Firewalls
  • IOS Firewalls

Logging

Sårbare Router Services

Sårbare Router interfaces

SNMP, NTP og DNS sårbarheder

Routenings protokoller sårbarheder

Routing Protocol Authentication

RIP version 2

EIGRP og OSPF

Cisco Auto secure

Cisco SDM (Secure Device Manager)

Configuring SDM

Starting SDM

SDM Wizards

SDM - One-Step Lockdown

Installer nyeste version af IOS

IOS Filsystemer

Filsystemer prefixer

copy kommando syntax

IOS filnavn opbygning

TFTP backup og upgrade af IOS image

Recovering lost IOS image via TFTP

Recovering lost IOS image via XMODEM

Cisco IOS Trouble shooting commands

using SHOW commands

using DEBUG commands

Recovering lost Router password

Opsummering