application intrusion detection

May 4, 1999 Application Intrusion Detection 1

Application Intrusion Detection

Robert S. Sielken

In Fulfillment Of

Master of Computer Science Degree

School of Engineering and Applied Science

University of Virginia


Outline

• Introduction

• State of Practice - OS IDS

• Case Studies

• Application Intrusion Detection

• Construction of an Application Intrusion Detection System (AppIDS)

• Conclusion


Introduction• Intrusion Detection

– determining whether or not some entity, the intruder, has attempted to gain, or worse, has gained unauthorized access to the system

• Intruders– Internal

– External

• Objectives– Confidentiality– Integrity– Availability– Accountability

• Current State– done at the OS level,

but diminishing returns– opportunities and limits

of utilizing application semantics?


State of Practice - OS IDS• Audit records

– operating system generated collections of the events that have happened in the system over a period of time

• Events– results of actions taken

by users, processes, or devices that may be related to a potential intrusion

• Threat Categories– Denial of Service

– Disclosure

– Manipulation

– Masqueraders

– Replay

– Repudiation

– Physical Impossibilities

– Device Malfunctions


OS IDS - Approaches• Anomaly Detection

– Static• Tripwire, Self-Nonself

– Dynamic• NIDES, Pattern

Matching (UNM)

• Misuse Detection• NIDES, MIDAS, STAT

• Extensions - Networks– Centralized

• DIDS, NADIR, NSTAT

– Decentralized• GrIDS, EMERALD


OS IDS - Generic Characteristics

• Relation - expression of how two or more values are associated– Statistical

– Rule-Based

• Observable Entities - any object (user, system device, etc.) that has or produces a value in the monitored system that can be used in defining a relation

• Thresholds - determine how the result of the relation will be interpreted


OS IDS - Generic Characteristics

• Effectiveness– fine-tuning of thresholds– frequency of relation evaluation– number of correlated values– hierarchy


AppIDS

• Guiding Questions– Opportunity – what types of intrusions can be

detected by an AppIDS?– Effectiveness – how well can those intrusions

be detected by an AppIDS?– Cooperation – how can an AppIDS cooperate

with the OS IDS to be more effective than either alone?


Case Studies• Electronic Toll

Collection– numerous devices

distributed

– complementary device values

– hierarchical

– gathers data about monitored external behavior

– accounting component

• Health Record Management– non-hierarchical

– no devices beyond controlling computer

– no financial component

– limited access

– contains physical realities

– data collection and scheduling components


Electronic Toll Collection (ETC)• Devices

– Toll Lane• Tag Sensor

• Automated Coin Basket

• Toll Booth Attendant

• Loop Sensor

• Axle Reader

• Weigh-In-Motion Scale

• Traffic Signal

• Video Camera

– Vehicle• Tag (Active/Passive)


ETC - Hierarchy

T o ll L a ne T o ll L a ne

T o ll P la za T o ll P la za

T o ll L a ne T o ll L a ne T o ll L a ne

T o ll P la za O th e r D e v ices

T o ll M a n ag e m en t C e n te r


ETC - Application Specific Intrusions

• Annoyance (3 methods)

• Steal Electronic Money (10 methods)

• Steal Vehicle (4 methods)

• Device Failure (1 method)

• Surveillance (2 methods)

Threat Categories

Specific Intrusions

Methods Relations


ETC - Steal Service

Rel#

RelationRelation

DescriptionExecutionLocation

Steal Service

No tagand

coverplate

Copytag

Packet filterthat discards

all a tag'spackets

1 Tag vs. Historical (Time) (stat) TBP/TMC X4 Tag vs. Historical (Sites) (stat) TMC X5 Tag vs. Time (rule) TMC X9 Tag vs. Axles (rule) TBL X X X25 Unreadable Tags (stat) TBP/TMC X


Application Intrusion Detection• Similarities

– detect intrusions by evaluating relations to differentiate between anomalous and normal behavior

– centralized or decentralized (hierarchical)

– same threat categories

• Differences– anomaly detection

using statistical and rule-based relations

– internal intruders

– event causing entity

– resolution

– tightness of thresholds

– event records• periodic

• code triggers


AppID (cont’d)• Dependencies

– OS IDS on AppIDS• None

– AppIDS on OS IDS• basic security services

• prevention of bypassing application to access application components

• Cooperation– audit/event record

correlation

– communication• bi-directional

• request-response bundles

– complications• terms of communication

• resource usage - lowest common denominator


Construction of an AppIDS

Event Record Manage

r

Relation Evaluato

r

Anomaly Alarm Handler

TOOLS

Relation Specifier

Relations

Event Record

Specifier

Event Record Structure

Timings

Relation – Code

Connector

Observable Entity Locations in the

Application

GENERIC COMPONENTS


Conclusion• Opportunity

– internal intruders (abusers)

– anomaly with statistical and rule-based relations

– same threat categories

• Effectiveness– resolution

– tightness of thresholds

• Cooperation– detection

• Construction– tools

– generic components


Health Record Management (HRM)

• Components– Patient Records– Orders – lists of all requests for drugs, tests, or

procedures– Schedule – schedule for rooms for patient

occupancy, laboratory tests, or surgical procedures (does not include personnel)

• Users– doctors, laboratory technicians, and nurses


HRM - Application Specific Intrusions

• Annoyance (4 methods)

• Steal Drugs (1 method)

• Patient Harm (6 methods)

• Surveillance (2 methods)

Threat Categories

Specific Intrusions

Methods Relations


HRM - Patient Harm

Rel#

RelationRelation

DescriptionPatient Harm

Adm

in.

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rug

Adm

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Too

Muc

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Dru

g

Adm

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an A

llerg

icD

rug

Adm

in.

Impr

oper

Die

t

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eed

less

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Per

form

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dles

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2 Drug vs. Allergy (rule) X X

5 Drug vs. Diet (rule) X X

8 Drug vs. Historical (dosage) (stat) X X

24 Patient Test Results vs. TestResults (Historical)

(stat) X X X X


ETC - Steal ServiceRel#

Relation Relation DescriptionExecutionLocation

Steal Service

No tagand

coverplate

Copytag


all a tag'spackets

1 Tag vs.Historical (Time)

Tag (Time of Day) should match Historical Time (ofDay) (stat)

TBP/TMC X

2 Tag vs.Historical (Day)

Tag (Day of Week) should match Historical Time(Day of Week) (stat)

TBP/TMC X

3Tag vs.

Historical(Frequency)

Tag (Frequency (per day)) should match HistoricalFrequency (per day) (stat)

TBP/TMC X

4 Tag vs.Historical (Sites)

Tag (Sites) should match Historical sites (stat) TMC X

5 Tag vs. TimeTag should not be reread within x minutes any othertoll both (rule)

TMC X

6 Tag vs. ParkingTag (Identity) should not be listed as being in aparking facility (Parking) (rule)

TMC X

7 Tag vs. Reportof Stolen Tag

Tag should not match that of a reported lost/stolenvehicle (rule)

TMC X

9 Tag vs. Axles Tag (Axles) should match Axles (rule) TBL X X X10 Tag vs. Scale Tag (Weight) should match Scale (rule) TBL X X X

11Tag + Toll +Coin Toll vs.Traffic Signal

# of tolls paid (tag/toll/coin-toll) equals number ofsignals given (green) (rule)

TBL X

12Tag + Toll +Coin Toll vs.

Video

# of tolls paid (tag/toll/coin-toll) equals number ofvehicles seen by camera (rule)

TBL X X

13Tag + Toll +Coin Toll vs.

Loops

# of tolls paid (tag/toll/coin-toll) equals number ofvehicles seen by loops (rule)

TMC X X


Steal Service (cont’d)Rel#

Relation Relation DescriptionExecutionLocation

Steal Service

No tagand

coverplate

Copytag


all a tag'spackets

15 Axles vs. Scale # of Axles should match Scale reading (rule) TBL X16 Axles vs. Toll Axles (cost) should match Toll collected (rule) TBL X X X

17 Axles vs. Coin-Toll

Axles (cost) should match Toll (coin) paid (rule) TBL X X X

18 Toll vs. Scale Toll collected should match Scale based fare (rule) TBL X X X

19 Toll vs. VideoToll collected should match Video vehicledetermination (rule)

TBL X X X

20 Coin-Toll vs.Scale

Toll (coin) paid should match Scale based fare (rule) TBL X X X

21 Coin-Toll vs.Video

Toll (coin) paid should match Video vehicledetermination (rule)

TBL X X X

22 Traffic Signal vs.Video

# of signals (green) equals # of vehicles seen byvideo camera (rule)

TBL X

23 Traffic Signal vs.Loops

# of signals (green) equals # of vehicles seen byloops (rule)

TMC X

24 Video vs. Loops# of vehicles seen by video camera equals # ofvehicles seen by loops (rule)

TMC X

25 UnreadableTags

# of unreadable tags should be fairly evenlydistributed between lanes and toll booths (stat)

TBP/TMC X


HRM - Patient HarmRel#

Relation Relation Description Patient Harm

Adm

in.

Wro

ngD

rug

Adm

in.

Too

Muc

hof

Dru

g

Adm

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an A

llerg

icD

rug

Adm

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Impr

oper

Die

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eed

less

Dru

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Per

form

Nee

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sP

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1 Drug vs. DrugCertain drugs cannot be taken in conjunction with otherdrugs (rule)

X

2 Drug vs. AllergyCertain drugs cannot be taken when a person has certainallergies (rule)

X X

3 Drug vs. SexCertain drugs cannot be taken by one sex or the other(rule)

X

4 Drug vs. WeightCertain drugs prescriptions are based on the patient'sweight (rule)

X X

5 Drug vs. DietCertain drugs cannot be taken while consuming certainfoods (rule)

X X

6 Drug vs. Lethal Dosage Drug dosage should not exceed the lethal dosage (rule) X X

7 Drug vs. TimeDrugs have a minimum time between doses (such as 4hours) (rule)

X X

8 Drug vs. Historical(dosage)

Drug dosage should be fairly similar to other prescriptionsof the drug in either dosage amount or frequency (stat)

X X

12 Procedure vs. DietSome procedures may have a special dietary preparationrequirement (rule)

X

18 Language vs.Language

Anything outside of the restricted language is not allowed(rule)

X

24Patient Test Results

vs. Test Results(Historical)

Test results should be related to previous test results forthat patient (stat)

X X X X

25 Test Results vs. TestResults (Historical)

Test results should be related to previous test resultsacross all patients (stat)

X X X X

application intrusion detection

Documents

system device

monitored system

os level

os idsbasic security

types of intrusions

state of practice

methodssteal vehicle

methodssteal electronic