CIT 380: Securing Computer Systems

CIT 380: Securing Computer Systems Slide #1

CIT 380: Securing Computer Systems

Reconnaissance


Domain Name Registration

Domain registration information– Contact information: names, email, phone– Postal address– Registration dates– DNS servers

Obtaining registration information– http://www.internic.net/whois.html– whois command

IP Address Assignments– Find ownership information for IP address blocks– http://ws.arin.net/whois


whoisDomain Name: NKU.EDURegistrant: Northern Kentucky University Information Technology Lucas Admin Center 507, Nunn Dr Highland Heights, KY 41099

Administrative Contact: Kathy Bennett (859) 572-1577 [email protected]

Technical Contact: Douglas Wells (859) 572-5847 [email protected]

Name Servers: NS3.NKU.EDU 192.122.237.203 NS4.NKU.EDU 192.122.237.204

Domain record activated: 12-Jul-1994Domain record last updated: 21-Sep-2007


whois> host intel.comintel.com has address 198.175.96.33> whois 198.175.96.33[Querying whois.arin.net][whois.arin.net]Intel Corporation NETBLK-INTEL-IT (NET-198-175-64-0-1) 198.175.64.0 - 198.175.123.255Distributed Network Technical Support INTEL-IT33 (NET-

198-175-96-0-1) 198.175.96.0 - 198.175.96.255

# ARIN WHOIS database, last updated 2004-04-04 19:15# Enter ? for additional hints on searching ARIN's

WHOIS database.


Threats

• Social Engineering– Pose as administrative contact via phone/email to gain

information

• Wardialing– Search telephone exchange for modems

• Domain Hijacking– 1998 redirect of aol.com to autonete.net

• Further network investigation– DNS queries– Network scans of IP address space


Domain Name Service (DNS)

Root DNS Servers

edu DNS servers com DNS servers net DNS servers

nku.edu DNS servers


DNS Lookup

Client Local DNS Svr

Root DNS Svr

edu DNS Svr

nku.edu DNS Svr

www.nku.edu

192.122.237.7

www.nku.edu

Referral to nku.edu

www.nku.edu

Referral to

edu

www.nku.edu192.122.237.7


DNS Record Types

Record Type Purpose

A Maps a DNS name to an IP address.

HINFO Arbitrary host information.

MX Identifies a mail server.

NS Identifies a name server.

TXT Arbitrary text used for documentation.


DNS ReconnaissanceIdentify hosts one by one using nslookup or dig commands.

$ nslookup> www.nku.eduNon-authoritative answer:Name: www.nku.eduAddress: 192.122.237.7> set type=mx> nku.eduNon-authoritative answer:nku.edu mail exchanger = 100 sort1.mxsmtp.com.nku.edu mail exchanger = 200 sort2.mxsmtp.com.nku.edu mail exchanger = 300 sort3.mxsmtp.com.

Authoritative answers can be found from:nku.edu nameserver = ns4.nku.edu.nku.edu nameserver = ns3.nku.edu.ns3.nku.edu internet address = 192.122.237.203


DNS Zone Transfer

List all DNS information for a domain– Used to sync secondary DNS servers with primary.– Provide entire DNS database to attacker.

Commands– host –l –v –t any nku.edu– nslookup

•set type=any•ls –d nku.edu

Defenses– ACL for zone xfers only f/ secondary DNS servers.– Separate internal and external DNS databases.


Network Mapping

• DNS and whois searches have identified networks of interest.

• Next step: mapping the networks• traceroute

– explore network topology– identify firewalls

• ping scan– find currently up hosts


traceroute> traceroute www.washington.edutraceroute: Warning: www.washington.edu has multiple addresses; using

140.142.11.6traceroute to www.washington.edu (140.142.11.6), 30 hops max, 40 byte packets 1 nku10 (192.122.237.10) 1.642 ms 1.195 ms 1.001 ms 2 h98.188.140.67.ip.alltel.net (67.140.188.98) 1.716 ms 1.219 ms 1.492 ms 3 h89.188.140.67.ip.alltel.net (67.140.188.89) 5.493 ms 5.850 ms 5.523 ms 4 128.163.55.209 (128.163.55.209) 21.311 ms 21.992 ms 21.349 ms 5 143.215.193.1 (143.215.193.1) 22.730 ms 21.956 ms 22.482 ms 6 216.24.186.34 (216.24.186.34) 37.851 ms 37.949 ms 37.459 ms 7 denv-chic-36.layer3.nlr.net (216.24.186.5) 61.102 ms 61.290 ms 61.864 ms 8 seat-denv-58.layer3.nlr.net (216.24.186.7) 87.954 ms 87.546 ms 87.563 ms 9 209.124.179.45 (209.124.179.45) 86.930 ms 86.932 ms 86.544 ms10 209.124.191.133 (209.124.191.133) 87.087 ms 86.794 ms 87.296 ms11 uwcr-ads-01-vlan1802.cac.washington.edu (205.175.101.9) 86.938 ms 87.157

ms 86.930 ms12 uwcr-ads-01-vlan3839.cac.washington.edu (205.175.101.158) 87.700 ms

86.899 ms 86.699 ms13 acar-ads-01-vlan3802.cac.washington.edu (205.175.108.10) 87.058 ms 87.061

ms 86.638 ms14 www14.cac.washington.edu (140.142.11.6) 87.439 ms 87.137 ms 87.303 ms


Network Diagramming

• traceroute to multiple internal hosts– identify different paths– identify firewalls that prevent traceroute

• Draw map of network based on traceroutes

• Helpful Tools• firewalk: route tracing tool that bypasses many

firewall configurations that stop traceroute

• neotrace: geographic map of network route


Defenses

Firewalls– Restrict ingress of packet types commonly used

for network mapping, e.g. ICMP.

Detection– IDS can detect network mapping attempts,

letting you know which IPs are mapping your network.


Ping Scanning

• Send IP packet to each IP address in a network, checking for responses.

• Scan types– ICMP echo– TCP port 80– TCP/UDP specific port– Fragmented packets


Ping Scanning> nmap -sP 10.17.0.0/24Starting nmap 3.50 (

http://www.insecure.org/nmap/ ) at 2004-04-05 13:57 EDT

Host pc_elan.lc3net (10.17.0.1) appears to be up.Host 10.17.0.31 appears to be up.Host 10.17.0.35 appears to be up.Host sun02 (10.17.0.55) appears to be up.Host sun09 (10.17.0.64) appears to be up.Host pc208p01 (10.17.0.66) appears to be up.Host sun14 (10.17.0.80) appears to be up.Host 10.17.0.241 appears to be up.Host 10.17.0.247 appears to be up.Nmap run completed -- 256 IP addresses (54 hosts

up) scanned in 4.510 seconds


Defenses

Firewalls– Refuse ICMP echo ingress.

– Restrict TCP ports to necessary servers• port 80 only to web server

• port 25 only to mail server

Bypassing defences– Multiple sweeps with different target ports.

– ICMP timestamp and netmask request queries.

– Fragment scans.


Ping Scan vs Firewall

Firewall Ruleset– pass from any to 10.0.17.31 port 53

– pass from any to 10.0.17.35 port 25

– drop all

> nmap -sP 10.17.0.0/24Starting nmap 3.50 at 2004-04-05 13:57Nmap run completed -- 256 IP addresses (0 hosts up) scanned in 72.430 seconds


Ping Scan vs Firewall

Firewall Ruleset– pass from any to 10.0.17.31 port 25 keep state– pass from any port 53 to any keep state– drop all

> nmap -sP –PS25 10.17.0.0/24– bypasses first rule, finds any hosts listening on port 25

> nmap -sP –g 53 10.17.0.0/24– bypasses second rule, as packets look like DNS

response


Key Points

1. Reconnaissance– Don’t forget about low tech means.

– Organizations give away info on web sites.

2. Registration– whois

– ARIN

3. DNS– Recursive DNS query process.

– Types of DNS records.

– Zone transfers.


References1. Matt Bishop, Introduction to Computer Security, Addison-Wesley,

2005.2. William Cheswick, Steven Bellovin, and Avriel Rubin, Firewalls and

Internet Security, 2nd edition, 2003.3. Fyodor, “The Art of Port Scanning,”

http://www.insecure.org/nmap/nmap_doc.html4. Fyodor, NMAP man page,

http://www.insecure.org/nmap/data/nmap_manpage.html5. Fyodor, “Remote OS detection via TCP/IP Stack FingerPrinting,”

Phrack 54, http://www.insecure.org/nmap/nmap-fingerprinting-article.html

6. Simson Garfinkel, Gene Spafford, and Alan Schwartz, Practical UNIX and Internet Security, 3rd edition, O’Reilly & Associates, 2003.

7. Johnny Long, Google Hacking for Penetration Testers, Snygress, 2004.8. Stuart McClure, Joel Scambray, George Kurtz, Hacking Exposed, 3rd

edition, McGraw-Hill, 2001.9. Ed Skoudis, Counter Hack Reloaded, Prentice Hall, 2006.

http://www.insecure.org/nmap/nmap_doc.html

http://www.insecure.org/nmap/data/nmap_manpage.html

CIT 380: Securing Computer Systems

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