Lecture Notes - Computer Science & Engineering

Download Report

Transcript Lecture Notes - Computer Science & Engineering

CSCE 727
Cyber Attacks and Risk
Management
Attack Sophistication vs.
Intruder’s Technical Knowledge
From: http://people.ubuntu.com/~duanedesign/SurvivabilityandInformationAssuranceCurriculum/01survive/01survive.html
CSCE 727 - Farkas
2
Reading
Required:
 Denning Chapter 8, 9, 14
 Hutchins et al, Intelligence-Driven Computer Network Defense Informed by
Analysis of Adversary Campaigns and Intrusion Kill Chains, White
paper,http://www.lockheedmartin.com/content/dam/lockheed/data/corporate/d
ocuments/LM-White-Paper-Intel-Driven-Defense.pdf
Interesting Reading:
 DHS repairing internal security operations, Homeland Security News Wire,
April 9, 2014, http://www.homelandsecuritynewswire.com/seworld20140409dhs-repairing-internal-security-operations
 Student develops new way to detect hackers, Homeland Security News Wire,
April 9, 2014, http://www.homelandsecuritynewswire.com/dr20140409student-develops-new-way-to-detect-hackers
 Measuring smartphone malware infection rates, Homeland Security News
Wire, April 9, 2014, http://www.homelandsecuritynewswire.com/dr20140409measuring-smartphone-malware-infection-rates
CSCE 727 - Farkas
3
Attack
Internet Engineering Task Force: RFC 2828:
“ An assault on system security that derives
from an intelligent threat, i.e., an intelligent
act that is a deliberate attempt (especially in
the sense of a method or technique) to
evade security services and violate the
security policy of the system.”
CSCE 727 - Farkas
4
Normal Flow
Information
source
CSCE 727 - Farkas
Information
destination
5
Interruption
Information
source
Information
destination
Asset is destroyed of becomes unavailable - Availability
Example: destruction of hardware, cutting communication
line, disabling file management system, etc.
CSCE 727 - Farkas
6
Interception
Information
source
Information
destination
Unauthorized party gains access to the asset – Confidentiality
Example: wiretapping, unauthorized copying of files
CSCE 727 - Farkas
7
Modification
Information
source
Information
destination
Unauthorized party tampers with the asset – Integrity
Example: changing values of data, altering programs, modify
content of a message, etc.
CSCE 727 - Farkas
8
Fabrication
Information
source
Information
destination
Unauthorized party insets counterfeit object into the system –
Authenticity
Example: insertion of offending messages, addition of records
to a file, etc.
CSCE 727 - Farkas
9
Phases of Attack
Improve detection by examining which “phase” an
intruder’s behavior is identified
 Attack phases:

– Intelligence gathering: attacker observes the system to
determine vulnerabilities
– Planning: attacker decide what resource to attack
(usually least defended component)
– Attack: attacker carries out the plan
– Inside the system:


Hiding: attacker covers tracks of attack
Future attacks: attacker installs backdoors for future entry
points
CSCE 727 - Farkas
10
Passive Attack
“Attempts to learn or make use of information
from the system but does not affect system
resources” (RFC 2828)
Sniffer
CSCE 727 - Farkas
11
Sniffers
All machines on a network can “hear”
ongoing traffic
 A machine will respond only to data
addressed specifically to it
 Network interface: “promiscuous mode” –
able to capture all frames transmitted on
the local area network segment

CSCE 727 - Farkas
12
Risks of Sniffers

Serious security threat
 Capture confidential information
– Authentication information
– Private data

Capture network traffic information
CSCE 727 - Farkas
13
Network Sniffing Tools






Used for network analysis and troubleshooting
SecTools.Org: Top 125 Network Security Tools,
http://sectools.org/tag/sniffers/
Free, open source sniffers
Multiplatform support (user needs superuser
privilege, education: drop privilege)
#1: Wireshark: GUI interface
#9: tcpdump: command line
CSCE 727 - Farkas
14
Wireshark




Examines data from a live network or from a capture
file on disk
GUI interface for editing and visualization
– Green: TCP traffic, dark blue: DNS traffic, light
blue: UDP traffic, black: TCP packets with
problems
Has remotely exploitable security holes
How to Use Wireshark to Capture, Filter and Inspect
Packets, http://www.howtogeek.com/104278/how-touse-wireshark-to-capture-filter-and-inspect-packets/
CSCE 727 - Farkas
15
Passive attacks
Interception (confidentiality)
Disclosure of message contents
CSCE 727 - Farkas
Traffic analysis
16
Disclosure of message content

Intruder is able to interpret and extract
information being transmitted
 Highest risk:authentication information
– Can be used to compromise additional system
resources
CSCE 727 - Farkas
17
Traffic Analysis

Intruder is not able to interpret and
extract the transmitted information
 Intruder is able to derive (infer)
information from the traffic characteristics
CSCE 727 - Farkas
18
Protection Against Passive
Attacks

Shield confidential data from sniffers:
cryptography
 Disturb traffic pattern:
– Traffic padding
– Onion routing

Detect and eliminate sniffers
CSCE 727 - Farkas
19
Detection of Sniffer Tools

Difficult to detect: passive programs
 Tools:
– Promisc – Linux
– cmp – SunOS 4.x: detects promiscuous mode
– AntiSniff (L0pht Heavy Industries, Inc. ): remotely
detects computers that are packet sniffing, regardless of
the OS
 Interesting read: S. Truth, How to Test for Sniffing
Vulnerabilities, http://web.securityinnovation.com/appsecweekly/blog/bid/63274/How-to-Test-for-SniffingVulnerabilities
CSCE 727 - Farkas
20
Tor

Online anonymity
 Free software and an open network
 Platforms: Windows, Mac, Linux/Unix, and
Android
 Defend against traffic analysis
 Download site: https://www.torproject.org/
CSCE 727 - Farkas
21
Tor

Tor network: a group of volunteer-operated
servers
 Privacy: user connections through a series
of virtual tunnels using the Tor network
 Censorship circumvention tool: allowing
users to reach otherwise blocked
destinations or content
CSCE 727 - Farkas
22
How Tor works?

Source:
https://www.torproject.org/about/overview.
html.en
 Cryptographically hide connection between
communicating partners
CSCE 727 - Farkas
23
Source: The Tor Project, https://www.torproject.org/
CSCE 727 - Farkas
24
Source: The Tor Project, https://www.torproject.org/
CSCE 727 - Farkas
25
Source: The Tor Project, https://www.torproject.org/
CSCE 727 - Farkas
26
Risk of Tor?




False sense of privacy
Legal risk of Tor relay operators?
Bad guys use Tor, too!
Interesting reading:
– EFF: 7 Things You Should Know About Tor, 2014,
https://www.eff.org/deeplinks/2014/07/7-things-you-shouldknow-about-tor
– B. Schneier: Has Tor Been Compromised?, 2013,
https://www.schneier.com/blog/archives/2013/08/has_tor_be
en_co.html
CSCE 727 - Farkas
27
Active attacks
“Attempts to alter system resources of affect
their operation” (Internet Enginering Task
Force, RFC 2828)
CSCE 727 - Farkas
28
Active attacks
Interruption
DOS, DDOS
(availability)
Modification
(integrity)
Replay
(Authentication)
Masquarade
(Authentication)
CSCE 727 - Farkas
Fabrication
(integrity)
29
Protection against DoS, DDoS

Hard to provide full protection
 Some of the attacks can be prevented
– Filter out incoming traffic with local IP address
as source
– Avoid established state until confirmation of
client’s identity

Internet trace back: determine the source of
an attack
CSCE 727 - Farkas
30
Degradation of Service

Do not completely block service just reduce
the quality of service
CSCE 727 - Farkas
31
Intrusion Control
It is better to prevent something than to plan
for loss.
Problem: Misuse happens!
CSCE 727 - Farkas
32
Need:

Intrusion Prevention: protect system
resources
 Intrusion Detection: (second line of
defense) identify misuse

Intrusion Recovery: cost effective recovery
models
CSCE 727 - Farkas
33
Intrusion Prevention

First line of defense
 Techniques: cryptography, identification,
authentication, authorization, access
control, security filters, etc.
 Not good enough (prevention,
reconstructions)
CSCE 727 - Farkas
34
Intrusion Detection System
(IDS)

Looks for specific patterns (attack
signatures or abnormal usage) that indicate
malicious or suspicious intent
 Second line of defense against both internal
and external threats
 See recommended reading!
CSCE 727 - Farkas
35
Intrusion Detection Systems

Deter intruders
 Catch intruders
 Prevent threats to fully occur (real-time
IDS)
 Improve prevention techniques
 IDS deployment, customisation and
management is generally not trivial
 See required reading!
CSCE 727 - Farkas
36
Audit-Based Intrusion
Detection
Profiles,
Rules, etc.
Audit Data
Intrusion Detection
System
Decision
CSCE 727 - Farkas
Need:
• Audit data
• Ability to characterize
behavior
37
Audit Data

Format, granularity and completeness depend on
the collecting tool
 Examples
–
–
–
–
System tools collect data (login, mail)
Additional collection of low system level
“Sniffers” as network probes
Application auditing

Honey Net
 Needed for
– Establishing guilt of attackers
– Detecting suspicious user activities
CSCE 727 - Farkas
38
Audit Data Accuracy

Collection method
– System architecture and collection point
– Software and hardware used for collection

Storage method
– Protection of audit data

Sharing
– Transmission protection and correctness
– Availability
CSCE 727 - Farkas
39
IDS Categories
1.
2.
3.
4.
5.
Time of data analysis
 Real-time v.s. off-the-line IDS
Location where audit data was gathered
 Host-based v.s. network-based v.s. hybrid
Technique used for analysis
 Rule-based v.s. statistic-based
Location of analysis
 Centralized, distributed, network-based
Pattern IDS looking for
 Misuse v.s. anomaly-based v.s. hybrid
CSCE 727 - Farkas
40
Intrusion Recovery





Actions to avoid further loss from intrusion
Terminate intrusion and protect against reoccurrence
Law enforcement
Enhance defensive security
Reconstructive methods based on:
– Time period of intrusion
– Changes made by legitimate users during the effected
period
– Regular backups, audit trail based detection of effected
components, semantic based recovery, minimal rollback for recovery.
CSCE 727 - Farkas
41
What is “Survivability”?
To decide whether a computer system is
“survivable”, you must first decide what
“survivable” means.
CSCE 727 - Farkas
42
Risk Assessment
Threats
RISK
Vulnerabilities
Consequences
43
Real Cost of Cyber Attack

Damage of the target may not reflect the
real amount of damage
 Services may rely on the attacked service,
causing a cascading and escalating damage
 Need: support for decision makers to
– Evaluate risk and consequences of cyber attacks
– Support methods to prevent, deter, and mitigate
consequences of attacks
44
Risk Management Framework
(Business Context)
Understand Business
Context
Identify Business
and Technical Risks
Carry Out Fixes
and Validate
Synthesize and Rank
Risks
Define Risk
Mitigation Strategy
Measurement and Reporting
45
Understand the Business Context
“Who cares?”
 Identify business goals, priorities and
circumstances, e.g.,

–
–
–
–

Increasing revenue
Meeting service-level agreements
Reducing development cost
Generating high return investment
Identify software risk to consider
46
Identify Business and Technical
Risks


“Why should business care?”
Business risk
– Direct threat
– Indirect threat

Consequences
–
–
–
–

Financial loss
Loss of reputation
Violation of customer or regulatory constraints
Liability
Tying technical risks to the business context in a
meaningful way
47
Synthesize and Rank the Risks
“What should be done first?”
 Prioritization of identified risks based on business
goals
 Allocating resources
 Risk metrics:

–
–
–
–
Risk likelihood
Risk impact
Risk severity
Number of emerging risks
48
Define the Risk Mitigation
Strategy
“How to mitigate risks?”
 Available technology and resources
 Constrained by the business context: what
can the organization afford, integrate, and
understand
 Need validation techniques

49
Carry Out Fixes and Validate

Perform actions defined in the previous
stage
 Measure “completeness” against the risk
mitigation strategy
– Progress against risk
– Remaining risks
– Assurance of mechanisms

Testing
50
Measuring and Reporting

Continuous and consistent identification
and storage of risk information over time
 Maintain risk information at all stages of
risk management
 Establish measurements, e.g.,
– Number of risks, severity of risks, cost of
mitigation, etc.
51
Assets-Threat Model (1)
Threats compromise assets
Threats have a probability of occurrence and
severity of effect
Assets have values
Assets are vulnerable to threats
Threats
Assets
52
Assets-Threat Model (2)
Risk: expected loss from the threat against an
asset
R=V*P*S
R risk
 V value of asset
 P probability of occurrence of threat
 V vulnerability of the asset to the threat

53
Risk Acceptance
Certification

How well the system meet the security
requirements (technical)
Accreditation

Management’s approval of automated system
(administrative)
54
Next Class: Privacy
CSCE 727 - Farkas
55