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Reconnaissance, Network Mapping, and Vulnerability Assessment

ECE4112 – Internetwork Security

Georgia Institute of Technology

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Agenda

• Reconnaissance

• Scanning

• Network Mapping

• Port Scanning

•OS detection

• Vulnerability assessment

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Reconnaissance

• Internet Network Information Center who-is

database www.internic.net/whois.html

• Registrar’s database i.e. www.networksolutions.com

• American Registry for Internet Numbers (ARIN)

http://ww2.arin.net/whois/

• Domain Name System (DNS) nslookup

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Reconnaissance

• After Recon, it is possible to know detailed information about a potential target

• This information includes specific IP addresses and ranges of addresses that may be further probed.

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Scanning

Objective 1: Network Mapping

Why: To determine what the network looks like logically.

How: Manually using tools like ping, traceroute, tracert, or with tools like Cheops network mapping tool

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Scanning

Objective 2: Port Scanning

Why: To find open ports in order to exploit them.

How:

• TCP Connect -- attempt to complete 3-way handshake, look for SYN-ACK, easy to detect this scan

• TCP SYN Scan -- “half-open” scan, look for SYN-ACK, then send RESET, target system will not record connection, also faster than TCP connect scan

• TCP FIN, Xmas Tree, Null Scans -- scans that violate the protocol, closed ports send RESET, open ports send nothing (Windows does not respond to these scans)

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Scanning

• TCP ACK Scan -- may be useful to get past packet filters (believes it is a response to a request from inside firewall), if receive RESET, know this port is open through firewall

• FTP Bounce Scan -- request that server send file to a victim machine inside their network (most servers have disabled this service)

• UDP Scan -- unreliable, if receive ICMP Port Unreachable, assume closed, otherwise open

• Ping Sweep -- can use ICMP or TCP packets

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Scanning

Additional objectives:

• Decoys -- insert false IP addresses in scan packets

• Ping Sweeps -- identify active hosts on a target network

• Find RPCs -- connect to each open port looking for common RPC services (send NULL RPC commands)

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Scanning

Objective 3: Operating System Detection

Why: To determine what Operating System is in use in order to exploit known vulnerabilities.

• Also known as TCP stack fingerprinting.

• Take advantage of ambiguity of how to handle illegal combinations of TCP code bits that is found in the RFCs.

• Each OS responds to illegal combinations in different ways.

• Determine OS by system responses.

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OS detection

Window Size: Most Unix Operating Systems keep the windowSize the same throughout a session. Windows Operating Systems tend to change the window size during a session.

Time to Live: FreeBsd or Linux typically use 64, Windows Typically uses 128.

Do Not Fragment Flag: Most OS leave set, OpenBSD leaves it unset.

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Nmap: Network Exploration Tool

Purpose: “To allow system administrators and curious individuals to scan large networks to determine which hosts are up and what services they are offering.”

Available at: http://www.insecure.org/nmap/

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Nmap: What does it do?

• Port scanning• OS detection• Ping sweeps

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Nmap: How does it work?

• UDP • FIN

• TCP connect() • ACK sweep

• TCP SYN (half open) • Xmas Tree

• ftp proxy (bounce attack) • SYN sweep

• Reverse-Identification • IP Protocol

• ICMP (ping sweep) • Null Scan

Use the following Scan techniques :

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Nmap: How does it work?

• Uses the following OS detection techniques• TCP/IP fingerprinting• stealth scanning• dynamic delay and retransmission calculations• parallel scanning• detection of down hosts via parallel pings• decoy scanning• port filtering detection• direct (non-port mapper) RPC scanning• fragmentation scanning• flexible target and port specification.

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Scanning Vulnerability Assessment (1)

Objective 4: Vulnerability Assessment

Why: To determine what known (or unknown?) vulnerabilities exist on a given network

Vulnerabilities come from:

• Default configuration weakness

• Configuration errors

• Security holes in applications and protocols

• Failure to implement patches!

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Vulnerability Assessment

Vulnerability checkers use:

• Database of known vulnerabilities

• Configuration tool

• Scanning engine

• Knowledge base of current scan

• Report generation tool

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Scanning tool: Nessus

Purpose: “To provide to the internet community a free, powerful, up-to-date and easy to use remote security scanner.”

Security Scanner: “A software which will audit remotely a given network and determine whether bad guys (aka 'crackers') may break into it, or misuse it in some way.”

Available platforms: UNIX for client and serverWindows for client only

Available at: http://www.nessus.org/

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Nessus: What does it do?

• Iteratively tests a target system (or systems) for known exploitation vulnerabilities

• Uses a separate plug-in (written in C or Nessus Attack scripting Language) for each security test

• Can test multiple hosts concurrently

• Produces a thorough vulnerability assessment report at the conclusion of the vulnerability scan

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What does Nessus check for?

• Backdoors

• CGI abuses

• Denial of Service

• Finger abuses

• FTP

• Gain a shell remotely

• Gain root remotely

• Port scanners

• Remote file access

• RPC

• SMTP problems

• Useless services

• Windows

• and more...

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Scanning tool: Superscan4 (windows XP)

Purpose: “To provide to the internet community a free, powerful, up-to-date and easy to use remote security scanner.”

Security Scanner: “Superior scanning speed, Support for unlimited IP ranges, Improved host detection using multiple ICMP methods , TCP SYN scanning , UDP scanning (two methods), IP address import supporting ranges and CIDR formats, Simple HTML report generation, Source port scanning, Fast hostname resolving, Extensive banner grabbing , Massive built-in port list description database , IP and port scan order randomization , A selection of useful tools (ping, traceroute, Whois etc) ,Extensive Windows host enumeration capability .”

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Lab Enhancements

What corrections and or improvements do you suggest for this lab? Please be very specific and if you add new material give the exact wording and instructions you would give to future students in the new lab handout. You may cross out and edit the text of the lab on previous pages to make minor corrections/suggestions. General suggestions like add tool xyz to do more capable scanning will not be awarded extras points even if the statement is totally true. Specific text that could be cut and pasted into this lab, completed exercises, and completed solutions may be awarded additional credit. Thus if tool xyx adds a capability or additional or better learning experience for future students here is what you need to do. You should add that tool to the lab by writing new detailed lab instructions on where to get the tool, how to install it, how to run it, what exactly to do with it in our lab, example outputs, etc. You must prove with what you turn in that you actually did the lab improvement yourself. Screen shots and output hardcopy are a good way to demonstrate that you actually completed your suggested enhancements.

“BAD ISP”AS 64700

“UNIVERSITY”AS 64900

“ENTERPRISE”AS 64800

“GOOD ISP”AS 64600

Version 11August 6, 2004GTISC Mini-Net

“TIER 1 - Sigma”AS 64515

“TIER 1 - omega”AS 64514 Omega-rtr

Cisco 2621-XM

Sigma1-rtrCisco 2621-XM

Sigma2-rtrCisco 3550

Badisp-rtrCisco 3550-24-EMI (L3)

StorageRus-rtr1760-K9

Cust2-rtrCisco 1720

Joe-travel-rtrCisco 1720

Gateway2-rtrCisco 3550-24-EMI (L3)

Admin-rtrCisco 1760-K9

CS2-rtrCisco 1720

CS-rtrCisco 1720

NASDell Network

Attached Storage

PWR

OK

WIC0ACT/ CH0

ACT/CH1

WIC0ACT /CH0

ACT /CH1

ETHACT

COL

Admin-vpnCisco VPNConc. 3005

Edge-fwallCisco PIX-515E

Edge1-rtrCisco 1760-K9

Edge2-rtrCisco 1760-K9

Gateway-rtrCisco 1760-K9

Accounting-rtrCisco 1720

Engineering-rtrCisco 1720

172.16.7.0/24:107

Goodisp-rtrCisco 3550-24-EMI (L3)

Cust1-site1-rtrCisco 1760-K9+NAT

Cust1-site2-rtrCisco 1760-K9+NAT

Cust1-hq-rtrCisco 1760-K9+NAT

Cust1-intr1-rtrCisco 1720

Cust1-intr2-rtrCisco 1720

Enterprise Web ServerRedhat Apache

http://www.enterprise.com

StorageRus WebserverMS IIS

http://www.storagerus.com

Cust1 WebserverRedhat Apache

http://www.cust1.com

CS WebserverRedhat Apache

http://www.cc.university.edu

Admin WebserverMS IIS

http://www.admin.university.edu

University WebserverRedhat Apache

http://www.university.edu

University-dnsDell Poweredge

Root1-dnsDell Poweredge

Badisp-dnsDell Poweredge

Goodisp-dnsDell Poweredge

NETWORK/MASK:VLAN Autonomous System

172.16.5.0/24:105

172.16.4.0/24:104

212.43.0.0/24:100

172.16.2.0/24:102

192.168.0.0/24:101

62.7.245.252/30:308

199.77.32.0/30:300

62.7.200.32/30:309

199.77.33.0/30:303

199.77.31.0/30:301

199.77.250.240/30:302

199.110.254.40/30:307

199.107.254.252/30:304

199.107.12.0/24:305

138.210.251.0/24:200

192.168.110.0/24:209

138.210.237.0/24:207

138.210.238.0/24:208

138.210.235.0/24:205

138.210.236.0/24:206

138.210.232.0/24:202

138.210.233.0/24:203

138.210.234.0/24:204

138.210.231.0/24:201

138.210.240.0/24:210

57.35.0.16/30:252

57.35.10.0/24:260

57.35.5.0/24:258

57.35.6.0/24:259 57.35.4.0/24:257

57.35.3.0/24:256

57.35.2.0/24:255

57.35.1.0/24:254

57.35.0.0/30:253

57.35.0.128/30:251

57.35.7.0/24:250

64.0.1.32/28:151

64.0.1.16/28:152

64.0.2.0/24:153

192.168.10.0/24:161

192.168.20.0/24:162

192.168.10.0/24:163

192.168.20.0/24:164

75.196.18.0/24:160

75.196.17.0/24:159

75.196.15.0/30:157

75.196.14.0/30:156

75.196.10.0/24:155

64.0.1.48/30:150

199.77.30.16/30:306

172.16.8.0/24:108

172.16.6.0/24:106

192.168.30.0/24:154

75.196.16.0/24:158

172.16.3.0/24:103

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EBGP

EBGP

EBGP

EBGP

EBGP EBGP

EBGP

IBGP

EBGP

RIPOSPF 0

OSPF 0OSPF 0

OSPF 1

RIP OSPF BGP

#23

#22

#24

#25

#4

#2

#20

#21

#19

#18

#1

#11

#8

#10

#7

#6

#12

#14 #15

#13

#17

#16

#26

9

R5

R4

R3

R1

R2

R6

R10

R11

R10

R10

Printer

.20

…W1 W20

R10

CS Ftp ServerRedhat

.43

R7

Enterprise-dnsDell Poweredge

.3R10

OSPF 0

Virtual IPAddresses

Bridge

XP honeypot

Redhat honeypot

138.210.228.0/24:211HUB

Honeynet

Honeynet

H3

H2

H1.1

.11

.10

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Summary

• Reconnaissance

• Scanning

• Network Mapping

• Port Scanning

• OS detection

• Vulnerability assessment