Integrity Through Mediated Interfaces PI Meeting Feb. 15, 2001 Bob Balzer, Marcelo Tallis...
-
Upload
howard-campbell -
Category
Documents
-
view
217 -
download
2
Transcript of Integrity Through Mediated Interfaces PI Meeting Feb. 15, 2001 Bob Balzer, Marcelo Tallis...
Integrity Through Mediated Interfaces
PI Meeting Feb. 15, 2001
Bob Balzer, Marcelo Tallis
Teknowledge
<balzer,mtallis>@teknowledge.comLegend: Turquoise Changes from July 99 PI meeting
Green Changes from Feb 00 PI meetingRed Changes from July 00 PI meeting
Technical Objectives
• Wrap Data with Integrity Marks– Insure its Integrity– Record its processing history– Reconstruct it from this history if it is corrupted
• by program bugs• by malicious attacks
• Demo these capabilities on major COTS product– Microsoft Office Suite (PowerPoint & Word only)– Also demo on a mission critical military system
• PowerPoint and Word
This Slide Intentionally Blank
Existing Practice
• Integrity Stove-Piped on Tool-by-Tool Basis
• End-to-End Integrity Not Supported
• Persistent Data only Safeguarded by OS
• Corruption Detection is Ad-Hoc
• Corruption Repair– Based on Backups– Not Integrated with Detection
• Wrap Program– Detect access of integrity marked data & decode it
M
M
M
M
Mediation Cocoon
Environment = Operating System External Programs
Program
ChangeMonitor
– Monitor User Interface to detect change actions• Translate GUI actions into application specific modifications
Technical Approach
– Detect update of integrity marked data • Re-encode & re-integrity mark the updated data
• Repair any subsequent Corruption from History• Build on existing research infrastructure
Major Risks and Planned Mitigation
• Ability to detect application-level modificationsApplication Openness Spectrum:– Event-Generators: Capture as transaction history– Scripting API: Examine state to infer action– Black-Box: Mediate GUI to infer action=> Generic Mediators + Tool Specific mapping
Two Level ArchitectureM
M
M
M
Mediation Cocoon
Environment = Operating System External Programs
Program
ChangeMonitor
1. Application Independent GUI Monitor signals action types
2. Application Dependent Change Monitor• Determines Action Parameters
• Logs Modification History
Major Risks and Planned Mitigation
• Ability to detect application-level modificationsApplication Openness Spectrum:– Event-Generators: Capture as transaction history– Scripting API: Examine state to infer action– Black-Box: Mediate GUI to infer action=> Generic Mediators + Tool Specific mapping
• Ability to protect transaction history=> Hide the location of the transaction history
• Virtual File System wrapper• System-level Randomization Techniques
• Tool-Specific Modification Trackers Expensive=> Automate common portions=> Provide rule-based scripting language
Accomplishments To Date
• Corruption Detector– IDs Document Version on Save (in Document)– Records Document Cryptographic Digest on Save– Checks Document Cryptographic Digest on Load
Demo
Demo
• Change Monitor for MS Word 2000– Determines parameters for application-level action– Records transaction history (for possible Replay)
• Corruption Repairer– Rebuilds document by replaying transaction history
Demo
• Operation Coverage– Compound Operations (Undo,AutoCorrect)– Recording “Uninstrumented” Operations
Demo
MS Word Data Integrity
Technical Approach To Attribution
• Time Lever shows document development– User selects range of interest– Move Forwards through Operations Log– Move Backwards through Undo Stack
Operations Log
Accomplishments To Date
• Corruption Detector– IDs Document Version on Save (in Document)– Records Document Cryptographic Digest on Save– Checks Document Cryptographic Digest on Load
Demo
Demo
• Change Monitor for MS Word 2000– Determines parameters for application-level action– Records transaction history (for possible Replay)
• Corruption Repairer– Rebuilds document by replaying transaction history
Demo
• Operation Coverage– Compound Operations (Undo,AutoCorrect)– Recording “Uninstrumented” Operations
Demo
• Attribution– Forward-Backward Time Control
Demo
MS Word Data Integrity Major Challenges
• Complexity of Word– 1128 unique commands
– 889 Command Bar controls
– 416 classes with 2594 instance variables
– However only a small subset is commonly used
• Lack of a General Mechanism for Capturing User Operations– Each individual Word function is handled in a specific
implementation.
MS Word Data Integrity
Majors Areas of Development• Capture of User Operations
– Mostly Word specific implementation– Impacted by complexity of Word
• Version Management and Recovery
• Attribution
MS Word Data Integrity
Capture of User Operations
Category
Total Implemented
N % N Coverage (%)
Common 19 7 17 89
Infrequent 42 16 8 19
Hardly Ever 205 77 0 0
• Status– Instrumented most GUI Interaction Mechanisms– Implemented most of the most used operations
Survey of Word operations usage(includes only text-based operations that modify document content)
MS Word Data Integrity
User Operation Capture Completion Strategy
• Detect UnInstrumented User Changes– Method: Unmediated change to Undo Stack
• Record Modification1. Localize Scope of Change
– Record Scoped Change
2. Checkpoint Document
PowerPoint Data Integrity
• Reuse existing capabilities– Corruption Detection Wrapper– Recording/Replay Mechanism– Office2000 Instrumentation– (PowerPoint) Design Editor Change Monitor
• Unique Development– Instrument Remaining PowerPoint Operations
Data Integrity
To Do• MS Word Data Integrity
– Finish set of commonly used operations (from survey)– Default mechanism to handle non instrumented
changes– Finish Attribution
• Power Point Data Integrity– We expect significant reuse of Word instrumentation
• Demonstrate Data Integrity in Military System– Identify mission critical Word/PowerPoint use– Package system for test deployment
Safe Email Attachments Accomplishments To Date
• Wrapper protects email attachment execution– Automatically spawned when attachment opened– Restricts
• Files that can be read/written• Remote Sites that can be downloaded-from/uploaded-to• Portions of Registry that can be read/written• Processes that can be spawned
Demo
• Email Attachment Context Determined• Alerts Logged with Context• AIA Experiment conducted with IMSC(Musman)
Required for Deployment
Safe Email Attachments
• Testing Status– Functionality Testing (MitreTek): Completed– Rule Testing (MitreTek): Imminent
• Allows normal behavior (Absence of False Positives)• Blocks malicious behavior
• To Do– Packaging for Deployment
• Installation• Documentation• Test for proper installation
– Implement Switch-Rules– Each attachment opened in separate process (hard)– Protect additional Resources (devices, COM)
Safe Email Attachments
• Planned Deployment– Aug: Alpha at Teknowledge/MitreTek– Sept: Beta at DARPA– Nov: Pilot at military command (TBD)
AprJun
Task Schedule
• Dec99: Tool-Level Integrity Manager– Monitor & Authorize Tool access & updates
• Jun00: Operation-Level Integrity Manager – Monitor, Authorize, & Record Modifications
• Dec00: Integrity Management for MS-Office• Jun01: Corruption Repair• Dec01: Integrity Management for
Mission Critical Military System• Jun02: Automated Modification Tracking
Word
Jun01: PowerPoint
Enforced Policies• MS Word documents (PowerPoint next)
– Attack: Document corrupted between usages– Policy: Check integrity when used. Rebuild if corrupted– Attack: Insider corrupts document using Word/PowerPoint– Policy: Log changes. Attribute changes to individuals
• Suspect Programs– Attack: Program may harm persistent resources– Policy: Copy files just before they are modified.
Rollback when requested• Email-Attachments (Web Browsers)
– Attack: Program may harm resources– Policy: Restrict access/modification of resources
• Executables– Attack: Unauthorized changes are made to executables– Policy: Integrity Check executables before loading
Prohibit unauthorized modification of executables
(To Be) Enforced Policies
• <Program> can’t leave any persistent files after it terminates
• <Program> can only create/access files in <directory> that are selected by user
• <Program> can only modify files it creates