TNC Proposals for NEA Protocols Presentation by Steve Hanna to NEA WG meeting at IETF 71 March 11, 2008

TNC Proposals for NEA Protocols2 PB-TNC

March 11, 2008TNC Proposals for NEA Protocols3 PB-TNC Purpose & Requirements PB Purpose –Carry PA messages between PBC & PBS –Carry global assessment decision from PBS to PBC –Carry other messages between PBC & PBS PB Challenging Requirements –MUST support half-duplex PT –MUST support grouping attributes to minimize RTs –MUST operate efficiently over low-bandwidth links –MUST carry PA message routing identifiers –SHOULD allow PBC or PBS to start assessment –MUST support adapting to user language preference –MAY include security measures or depend on PT security

March 11, 2008TNC Proposals for NEA Protocols4 PB-TNC Design Features Simple round-robin state machine –PBS or PBC can start by sending a batch –PBS & PBC take turns sending batches –End with PBS sending result or early close Compact batch & message format (Binary TLV) Designed for extensibility –No short fields, several reserved fields, versioning support –IANA process for standard extensions –Vendor IDs for non-standard extensions (cannot be required) PA message routing by PA message type –Optional delivery by PC/PV ID No PB-TNC security, depends on PT

March 11, 2008TNC Proposals for NEA Protocols5 PB-TNC State Machine CRETRY CDATA | Server |< | Decided | CLOSE >| Working | >| | | RESULT | | ^ | | v | | | >======= ======== | | CLOSE " End " " Init " CDATA or| |SDATA or ======= ======== CRETRY| |SRETRY ^ ^ | | | v | | | | SDATA CLOSE | | | >| Client | | | | Working | | | | | CLOSE |

March 11, 2008TNC Proposals for NEA Protocols6 PB-TNC Encapsulation PT PB-TNC Header PB-TNC Message (Type=PB-Batch-Type, Batch-Type=CDATA) PB-TNC Message (Type=PB-PA) PA Message PB-TNC Message (Type=PB-PA) PA Message

March 11, 2008TNC Proposals for NEA Protocols7 PB-TNC Header |Version| Reserved | | Batch Length |

March 11, 2008TNC Proposals for NEA Protocols8 PB-TNC Message | Flags | PB-TNC Vendor ID | | PB-TNC Message Type | | PB-TNC Message Length | | PB-TNC Message Value (Variable Length) |

March 11, 2008TNC Proposals for NEA Protocols9 IETF Standard PB-TNC Message Types Message Type Definition PB-Experimental - reserved for experimental use 1 PB-Batch-Type - indicates the type of the PB-TNC batch that contains this message 2 PB-PA - contains a PA message 3 PB-Access-Recommendation - includes Posture Broker Server access recommendation (also known as global assessment decision) 4 PB-Remediation-Parameters - includes Posture Broker Server remediation parameters 5 PB-Error - error indicator 6 PB-Language-Preference - sender's preferred language(s) for human-readable strings 7 PB-Reason-String - string explaining reason for Posture Broker Server access recommendation

March 11, 2008TNC Proposals for NEA Protocols10 PB-TNC Batch-Type Message | Flags | PB-TNC Vendor ID | | PB-TNC Message Type | | PB-TNC Message Length | |D| Reserved | Batch Type |

March 11, 2008TNC Proposals for NEA Protocols11 PB-TNC Batch Types Number Name CDATA 2 SDATA 3 RESULT 4 CRETRY 5 SRETRY

March 11, 2008TNC Proposals for NEA Protocols12 PB-PA Message | Flags | PB-TNC Vendor ID | | PB-TNC Message Type | | PB-TNC Message Length | | Flags | PA Message Vendor ID | | PA Subtype | | Posture Collector Identifier | Posture Validator Identifier | | PA Message Body (Variable Length) |

March 11, 2008TNC Proposals for NEA Protocols13 Questions about PB-TNC?

March 11, 2008TNC Proposals for NEA Protocols14 PA-TNC

March 11, 2008TNC Proposals for NEA Protocols15 PA-TNC Purpose & Requirements PA Purpose –Carry attributes between PCs & PVs PA Challenging Requirements –MUST support extensible set of standard attributes –MUST support extensible set of vendor-specific attributes –MUST support Posture Request attributes –MUST support half-duplex PT –MUST support grouping attributes to minimize RTs –MUST operate efficiently over low-bandwidth links –SHOULD provide security

March 11, 2008TNC Proposals for NEA Protocols16 PA-TNC Design Features Use message routing (PA Subtype) to ID component –Anti-Virus, Firewall, HIPS, OS, VPN, etc. Realize that most attributes apply across all components –Manufacturer, product ID, version, operational status, attribute request –So provide a standard way to describe these attributes, but allow extensions Use compact message format (Binary TLV) Design for extensibility –No short fields, several reserved fields –IANA process for standard extensions –Vendor IDs for non-standard extensions (cannot be required) Separate PA-TNC security since WG was uncertain

March 11, 2008TNC Proposals for NEA Protocols17 PA-TNC Within PB-TNC PT PB-TNC Header PB-TNC Message (Type=PB-Batch-Type, Batch-Type=CDATA) PB-TNC Message (Type=PB-PA, PA Vendor ID=0, PA Subtype= OS) PA-TNC Message PA-TNC Attribute (Type=Product Info, Product ID=Windows XP) PA-TNC Attribute (Type=Numeric Version, Major=5, Minor=3,...)

March 11, 2008TNC Proposals for NEA Protocols18 IETF Standard PA Subtypes Number Name Testing 1 Operating System 2 Anti-Virus 3 Anti-Spyware 4 Anti-Malware 5 Firewall 6 IDPS 7 VPN

March 11, 2008TNC Proposals for NEA Protocols19 PA-TNC Message Header | Version | Reserved | | Message Identifier |

March 11, 2008TNC Proposals for NEA Protocols20 PA-TNC Attribute | Flags | PA-TNC Attribute Vendor ID | | PA-TNC Attribute Type | | PA-TNC Attribute Length | | Correlation ID | | Attribute Value (Variable Length) |

March 11, 2008TNC Proposals for NEA Protocols21 IETF Standard PA-TNC Attribute Types Number Name Testing 1 Attribute Request 2 Product Information 3 Numeric Version 4 String Version 5 Operational Status 6 Port Filter 7 Installed Packages 8 PA-TNC Error

March 11, 2008TNC Proposals for NEA Protocols22 Main Types Defined in PB-TNC and PA-TNC PB-TNC Message Type –PB-Batch-Type, PB-PA, etc. PB-TNC Batch Type –CDATA, SDATA, etc. PA Subtype –Operating System, Anti-Virus, etc. PA-TNC Attribute Type –Product Information, Numeric Version, etc. All easily extensible except PB-TNC Batch Type –Via PEN for vendor-specific values –Via IANA registry for standard values

March 11, 2008TNC Proposals for NEA Protocols23 Questions about PA-TNC?

March 11, 2008TNC Proposals for NEA Protocols24 PA-TNC Security

March 11, 2008TNC Proposals for NEA Protocols25 PA-TNC Security Purpose & Requirements PA-TNC Security Purpose –Secure attributes between PCs & PVs PA-TNC Security Challenging Requirements –SHOULD provide authentication, integrity, and confidentiality protection of PA attributes –[If security protection is included,] MUST protect against active and passive attacks by intermediaries and endpoints including replay attacks –MUST operate efficiently over low-bandwidth links

March 11, 2008TNC Proposals for NEA Protocols26 PA-TNC Security Design Features Use Cryptographic Message Syntax (CMS) to secure PA-TNC messages –Avoids need for roundtrips to establish session keys –Allows for granular use of PA-TNC security only when desired –Allows for authentication without confidentiality –Extensible for nonce and capabilities exchange Allow protection of multiple attributes at once –Reduces bandwidth Assume that PCs and PVs handle authorization

March 11, 2008TNC Proposals for NEA Protocols27 CMS Protected Content PA-TNC Attribute Type New PA-TNC Attribute Type May be contained in any PA Subtype Contains CMS ContentInfo structure –May have signed-data or enveloped-data

March 11, 2008TNC Proposals for NEA Protocols28 signed-data Used when confidentiality protection is not needed encapContentInfo MUST contain one or more PA-TNC attributes certificates MUST include signer’s certificate and SHOULD include certificate path to trust anchor crls MAY include CRLs Only one SignerInfo permitted –MUST include signedAttrs with Nonce CMS attribute MUST: RSA 2048 & SHA-256 MUST-: SHA-1 SHOULD: ECDSA 256

March 11, 2008TNC Proposals for NEA Protocols29 Nonce CMS Attribute Provides replay protection MUST be included in all signedAttrs Includes pcNonce and pvNonce fields –PC & PV select unpredictable initial values –Increment to 2^32-1, then reselect

March 11, 2008TNC Proposals for NEA Protocols30 enveloped-data Used when confidentiality protection is needed encryptedContentInfo MUST contain encrypted version of signed-data originatorInfo MUST include signer’s certificate and SHOULD include certificate path to trust anchor, MAY include CRLs recipientInfo contains encryption keys for recipients

March 11, 2008TNC Proposals for NEA Protocols31 enveloped-data Algorithms Content EncryptionMUST AES 128 & 256 Key TransportMUST RSA wrap AES CEK 2048 Key AgreementMUST ESDH w/ AES KEK (128 & 256) Previously Distributed Symmetric KEK MUST AES Key Wrap (128 & 256) Password BasedMUST Password Derived AES (128 & 256) (if sptd)

March 11, 2008TNC Proposals for NEA Protocols32 Security Capabilities PA-TNC Attribute Type Used to indicate prioritized list of supported algorithms May be contained in any PA Subtype May be requested with Attribute Request Contains signed-data with Nonce and paTncSecurityCapabilities in SignerInfo’s signedAttrs and empty encapContent

March 11, 2008TNC Proposals for NEA Protocols33 Concerns with PA-TNC Security Need review by CMS experts Concern about data size Concern about complexity for PC & PV Concern about difficulty of configuring PC & PV authorization

March 11, 2008TNC Proposals for NEA Protocols34 Questions about PA-TNC Security?