Transcript IDS and IPS - Catatan Hasdi Putra

Network Intrusion Detection
Systems
MM Clements
A Adekunle
Lecture Overview
• Taxonomy of intrusion detection system
• Promiscuous & Inline Mode Protection: IDS, IPS
• IDS and IPS Deployment Considerations &
example
• Cisco IDS family
• Snort
• IDS/IPS Vulnerabilities
• How to protect IDS?
• Unified Threat Management (UTM)
• Summary
Engineering and Management of Secure Computer Networks
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Intrusion Detection
• Detection and protection
from attacks against
networks
• Three types of network
attacks
– Reconnaissance
– Access
– Denial of service
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Intrusion detection system (IDS)
• An Intrusion detection system (IDS) is software or
hardware designed to monitor, analyze and respond
to events occurring in a computer system or network
for signs of possible incidents of violation in security
policies.
– These incidents of violations can be unwanted attempts to
access, manipulate or disable computer systems, mainly via a
network, such as the Internet.
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Classification of Intrusion Detection
• Profile or Anomaly based intrusion detection
– Monitors network traffic and compares it against an
established baseline for normal use
• Bandwidth, protocols, ports and devices generally connecting
to each other
– Alerts the administrator or user when traffic is
detected which is anomalous, or significantly
different, than the baseline.
– Example: Snort Spade plug-in
– Prone to high number of false-positives
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Classification of Intrusion Detection
• Signature based intrusion detection
– Also known as Misuse Detection
• A signature based IDS will monitor packets on the network
and compare them against a database of signatures or
attributes from known malicious threats.
• Similar to the way most antivirus software detects malware.
– Examples: Cisco Sensors 4200 series, Snort
– Less prone to false positives
– Unable to detect zero-day threats whose signatures
are not available
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Signature based intrusion detection
• Signatures
– A set of patterns pertaining to typical intrusion
activity that, when matched, generate an alarm
• Signature Types
– Atomic—Trigger contained in a single packet
• Example: Looking for the pattern “/etc/passwd “in the
traffic
– Composite—Trigger contained in a series of multiple
packets
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Types of Intrusion Detection Systems
• Host based intrusion detection Systems
– Software (Agents) installed on computers to monitor input
and output packets from device
– It performs log analysis, file integrity checking, policy
monitoring, rootkit detection, real-time alerting and active
response.
– Examples:
• Cisco Security Agent (CSA) , OSSEC, Tripwire
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Host-Based Intrusion Detection
Corporate
network
Agent
Agent
Firewall
Agent
Agent
Agent
Untrusted
network
Agent
Agent
WWW
server
Engineering and Management of Secure Computer Networks
Agent
DNS server
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Types of Intrusion Detection Systems
• Network-Based Intrusion Detection Systems
– Connected to network segments to monitor, analyze and
respond to network traffic.
– A single IDS sensor can monitor many hosts
– NIDS sensors are available in two formats
• Appliance: It consists of specialized hardware sensor and its
dedicated software. The hardware consists of specialized NIC’s,
processors and hard disks to efficiently capture traffic and perform
analysis.
– Examples: Cisco IDS 4200 series, IBM Real Secure Network
• Software: Sensor software installed on server and placed in
network to monitor network traffic.
– Examples: Snort, Bro, Untangle
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Network-Based Intrusion Detection
Corporate
network
Sensor
Sensor
Firewall
Untrusted
network
Management
System
Engineering and Management of Secure Computer Networks
WWW
server
DNS
server
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Sensor Appliance Interfaces
Untrusted
Network
Monitoring Interface
Router
Switch
Sensor
Router
Protected
Network
Command and
Control Interface
Management System
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Promiscuous-Mode Protection: IDS
1
A network device sends copies
of packets to the sensor for analysis.
2
If the traffic matches a signature,
the signature fires.
Switched Port Analyzer (SPAN)
Switch
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The sensor can send an alarm
to a management console and
take a response action such as
resetting the connection.
Management
System
Engineering and Management of Secure Computer Networks
Sensor
Target
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Inline-Mode Protection: IPS
The sensor resides in the
data forwarding path.
An alert can be
sent to the
management console.
Management
System
Sensor
If a packet triggers a
signature, it can be
dropped before it
reaches its target.
Target
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Engineering and Management of Secure Computer Networks
IDS and IPS Deployment Considerations
– Deploy an IDS sensor in areas where you cannot
deploy an inline device or where you do not plan
to use deny actions.
– Deploy an IPS sensor in those areas where you
need and plan to use deny actions.
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IDS and IPS Deployment Comparison
Inside
Attacker
Internet
Sensor on Outside:
Sensor on Inside:
• Sees all traffic destined for
your network
• Sees only traffic permitted
by firewall
• Has high probability of raising
false alarms (false positives)
• Has lower probability of false
alarms (false positives)
• Does not detect internal
attacks
• Requires immediate
response to alarms
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Network based IDS and IPS Deployment
Switch
Switch
Firewall
Router
IPS Sensor
Management
Server
IDS
Sensor
Switch
Untrusted
Network
Corporate
Network
WWW
Server
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DNS
Server
DMZ
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IDS and IPS deployment example in an
Enterprise Network
Branch
Corporate
Network
NM-CIDS
Router Firewall
Untrusted
Network
Sensor
Sensor
Management
Server
DMZ
Agent
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WWW
Server
Agent
DNS
Server
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Cisco IDS Family
Performance (Mbps)
600
250
IDSM-2
IDS 4255
200
IPS 4240
80
AIP-SSM
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NM-CIDS
10/100/1000 TX
IPS 4215
10/100 TX
10/100/1000 TX
10/100/1000 TX
1000 SX
Network Media
10/100/1000 TX
Switched/1000
Snort
• Open source, freely available software except for rules
• Installed as dedicated server on Windows and Linux,
Solaris operating systems
• Placed as network sensor in a network
• Rules are set of instructions defined to take certain
action after matching some sort of signatures (atomic
or composite)
• Example:
• alert tcp $HOME_NET any -> $EXTERNAL_NET any
(content:"uk.youtube.com”;msg:"someone visited YouTube";)
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Snort Modes
• Sniffer Mode
• Used to sniff traffic from network
• Traffic will be captured using libpcap or winpcap.
• Traffic will be captured directly from the sensor .
• Logger Mode
• Simple logging into a file. Two possible formats are Binary and ASCII.
• Logging into a Database (eg. MySQL)
• Can be used for creating the normal traffic profile
• Intrusion Detection / Prevention
• The rules will be used in this mode of snort to detect unwanted activity
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IDS/IPS Vulnerabilities
• Cisco IPS Packet Handling DoS • In July 2006, a DoS vulnerability was discovered on Cisco
IPS 4200 series models which were running version 5.1
software.
• Snort Rule Matching Backtrack DoS • Snort versions 1.8 through 2.6 had a DoS vulnerability ,
found on January 11, 2007 which can exploit Snort's rule
matching algorithm by using a crafted packet. This could
cause the algorithm to slow down to the point where
detection may become unavailable. Snort was quick to
release version 2.6.1 which corrected this issue.
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How to protect IDS?
• Don't run any service on your IDS sensor.
• The platform on which you are running IDS should be
patched with the latest releases from your vendor.
• Configure the IDS machine so that it does not
respond to ping (ICMP Echo-type) packets.
• User accounts should not be created except those
that are absolutely necessary.
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Unified Threat Management (UTM)
• Unified Threat Management (UTM) is a
network device that have many features in
one box, including:
– IDS, IPS, Firewall, Spyware, Anti Spam , Anti
Phishing
– Anti Virus, Content (www) Filter, VPN
– Example: Untangle, Watchguard
– Untangle Demo:
http://www.untangle.com/video_overview/
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Computer Networks
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Summary
• Intrusion detection system (IDS) is software or hardware designed to
monitor, analyze and respond to network traffic .
– Can be classified as Profile or Signature based intrusion detection.
• Signatures can be defined as Atomic or Composite.
– Can be available as Host or Network based Intrusion detection .
– IDS is used as promiscuous mode protection in DMZ
– IPS is used as Inline mode protection for securing internal network
– Cisco 4200 series IDS and IPS sensors offer rich set of features for ISD
and IPS
– Snort is an open source, free IDS and can operate in sniff , logging and
Intrusion detection/prevention modes. Snort uses rules to analyze
traffic.
– IDS/IPS software can be vulnerable to exploits so run patched version,
and shutdown unnecessary services.
• Unified Threat Management (UTM) is a network device that have many
features in one box. E.g, Untangle, Watchguard.
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