Post on 30-Dec-2015
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The Pseudo-Internal Intruder: A New Access Oriented Intruder Category
Master’s Thesis Presentation
Brownell K. CombsMay 7, 1999
Outline
Why are we concerned with intruders and what can we do about them?
How does categorizing intruders help intrusion detection research?
What is the Pseudo-Internal Intruder?What can the Pseudo-Internal Intruder do?How can we defend against it?How do these defenses work?
The Problem of Intrusions
CSI/FBI 1999 Computer Crime and Security Survey (4th Annual Report) Approx. $124,000,000 in Financial Losses Only 1% Claimed No Security Incident
CERT statistics show 67% increase in incidents handled annually from ‘94 to ‘98
Intrusion Detection Systems
Many think that it may never be possible to create ‘completely secure’ systems
IDS is the next best thing Owners of systems want one or more of
the following: recognize presence of an intruder prevent them from doing harm make similar future intrusion more difficult attempt to catch the intruder
IDS Research
Studying Intruders (techniques, habits, etc) is an important area of IDS research
Researchers in the field and IDS builders in industry must have some scheme with which to categorize intruders
These schemes serve as a basic framework for discussing and thinking about the issue of Intrusion Detection
Intruder Categories
2 main approaches to placing intruders into different categories
Intruder oriented: focus on the intruder’s access to the system Anderson’s classic external/internal scheme
Attack oriented: focus on the attack the intruder executes Neumann’s modes of compromise scheme
What scheme do we need?
Least amount of category ambiguity for IDS Designers and SysAdmins
This best provided by narrowly defined categories that are distinct from one another Example: How useful is it to have an
‘external intruder’ category that refers to both Internet Hackers and janitors inside the building?
Definitions
Physical Configuration - all of the hardware used in a distributed system included the location of each item
Network Configuration - how all of those hardware items are connected and how they interact with each other
Net/Phy Perimeter - separation between a distributed system’s net/phy configuration and the rest of the world.
Pseudo-Internal Intruder
A new distinct category for the access oriented intruder categorization scheme
P-I Intruder is an intruder without the privileges of an authorized user and who has circumvented the perimeter defenses of a system to attack the system via its internal network (network configuration)
3 kinds of P-I Intruders
Insiders with physical access (desktop connection, wiring closets, server rooms)
Outsiders with same physical access as above (gained through subterfuge or force)
Outsiders with special data access (personal modems that circumvent perimeter defense)
Tools and Techniques
1) Network Assessment Tools Active and Passive
2) Packet Sniffers Hardware and Software
3) Exploits Steps executed in a certain order
4) Denial of Service Attacks Network Saturation and Traffic Misdirection
Example Scenario #1: Industrial Espionage Agent
#1 gains employment with custodial services and has access to wiring closets
Connects a hardware sniffer to the network for several days
Removes the sniffer and finds it captured sensitive communications between senior company executives
Mission Accomplished
Example Scenario #2: Disgruntled Employee
#2 is a basic network user with access to multiple desktop connection
Runs a network assesment tool and software sniffer off of a shared machine
Finds multiple vulnerabilities and an account and password of a SysAdmin
Logs in as SysAdmin (becomes an Internal Intruder) and deletes databases.
Mission Accomplished
Defending Against the Pseudo-Internal Intruder
Three phases: Deny intruders access to the system Mitigate the consequences of intruders
gaining access to the system Detect, Monitor, and Record any intrusions
Since Pseudo-Internal Intruders require access to the internal network, we will focus on it when examining these steps
Preventing Intruder Access
Physical Perimeter Security: stop as many potential intruders as possible from gaining physical access to the system (Guards, Gates, Locked Doors, etc.)
Physical configuration control: ensuring that unauthorized hardware is not introduced to the system and authorized hardware is not used for unauthorized actions (TEMPEST, Conduit, Metal Cases)
Mitigating Intruder Access
If an intruder cannot read information or write (affect a change) to the system then the danger of an intruder is diminished
Network configuration control: managing the aspects of the network configuration to ensure the highest degree of security Encrypt Communications, Switched-Intelligent
hubs and routers, smaller segments, etc.
Detecting Intruder Access
Network configuration monitoring: continuously observing all aspects of the network configuration searching for evidence of intruders
If an intruder does gain access to the system the most effective response will be a human one. Successful monitoring and reporting allows a quick response from SysAdmins
Case Study - Two Phases
Execute a set of Pseudo-Internal Intruder attacks against a testbed system with state of practice security measures CSI/FBI ‘99 Survey showed only 42 out of 501
respondents used any intrusion detectionExecute the same set of attacks against
the testbed system after implementing the security recommendations of the thesis
Case Study - The Attacks
1)Packet Sniffer – Software [Laptop] 2)Network Assessment Tool – Active [Rogue
Outside Connect] 3)Exploit – Ping of Death [Laptop] 4)Exploit (Hacker Program) – WinNuke (Ping
of Death) [Laptop] 5)Denial of Service Attack – Ping Flood
[Laptop] 6)Denial of Service Attack – Smurf Attack
[Rogue Outside Connect]
Case Study - Changes made for Phase 2
Network divided into 2 segmentsAll Mission Crit. Communication
EncryptedNetwork Intrusion Detection Monitoring
Device placed in Mission Crit. SegmentNetwork scanned for unknown IP and
MAC addressesRMON monitoring utilities used
Case Study - The Results
Security Changes addressed the vulnerabilities discovered in phase 1 No access control for devices using network No network traffic control mechanisms No internal network monitoring for
intrudersNetwork Configuration Monitoring and
Network Configuration Control decrease the danger of a P-I Intruder to systems
Conclusions
The Pseudo-Internal Intruder Category addresses an area of system security that did not exist prior to the proliferation of distributed systems
The category provides a platform on which to understand and define the capabilities of this new type of intruder, thereby facilitating the detection and defense against such intruders
Access Oriented: Anderson
External: unauthorized users attacking a system through external data connections
Internal: Legitimate: authorized for part of system Masqueraders: unauthorized users logged in
as legitimate users Clandestine: users logged in that have the
power to turn off some audit logs