BATTLE OF SKM AND IUM

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MAILBOXES • Secure Communications Channel between IUM and NTOS • Each Secure Process can have up to 8 Mailbox Slots • Once a slot is ‘filled’, it must be retrieved before it can be used again • Each slot can contain up to 4092 bytes of data (4 bytes are used to store the size, for a total of 1 page) • PostMailbox will fill a slot on the IUM side • SKM side uses SkRetrieveMailbox to read the data, and then performs a Normal Mode Service Call to copy the mailbox data to NTOS • NTOS can access mailboxes by using the VslRetrieveMailbox API which is exported by the kernel
SKM CAPABILITIES • The SkCapabilities array defines certain IUM System Calls that can be access controlled on an individual Trustlet basis using one of the following rules • AllowAll • CheckByTrustletId • CheckByTrustletInstanceGuid • SecureStorageGet and SecureStoragePut are the two IUM System Calls that currently check for capabilities • The Get API only allows Trustlet ID 2 to call it • The Set API only allows Trustlet ID 3 to call it • This implies a certain hardcoded knowledge of Trustlets baked into SKM
Page 1 and 2: BATTLE OF SKM AND IUM HOW WINDOWS 1
Page 3 and 4: PRESENTATION OVERVIEW • Microsoft
Page 5 and 6: VBS FEATURES IN WINDOWS 10 / SERVER
Page 7 and 8: ENABLING VBS
Page 9 and 10: HOW DOES IT ALL WORK? • Hyperviso
Page 11 and 12: SEPARATION OF ROLES • Instead of
Page 13 and 14: PLATFORM REQUIREMENTS • The Boot
Page 15 and 16: HARD CODE GUARANTEES • When hard
Page 17 and 18: VIRTUAL SECURE MODE (VSM) BOOTSTRAP
Page 19 and 20: SKM LAUNCH • To initialize VTL 1,
Page 21 and 22: BCD VSM POLICY OPTIONS • The poli
Page 23 and 24: SKM INTERNALS
Page 25: SKM STRUCTURES • SKM has a PCR at
Page 29 and 30: SECURE MODE CALLS • Secure Mode C
Page 31 and 32: SPECIALIZED SECURE MORE SERVICE CAL
Page 33 and 34: NORMAL MODE SERVICE CALLS • SK ne
Page 35 and 36: IUM INTERNALS
Page 37 and 38: SECURE SYSTEM CALLS • SKM exposes
Page 39 and 40: SECURE BASE API • Trustlets shoul
Page 41 and 42: NOTABLY MISSING… • Trustlets ca
Page 43 and 44: NORMAL MODE SYSTEM CALL PROXYING Th
Page 45 and 46: LAUNCHING A TRUSTLET • Process At
Page 47 and 48: EXAMPLE IUM-COMPLIANT SIGNED BINARY
Page 49 and 50: TRUSTLET INSTANCE GUID • Trustlet
Page 51 and 52: LSA TRUSTLET • One of the two inb
Page 53 and 54: LOADING A TRUSTLET • Ldr, or the
Page 55 and 56: TRUSTLET TO NORMAL WORLD COMMUNICAT
Page 57 and 58: CAN WE BUILD OUR OWN TRUSTLETS? •
Page 59 and 60: CONCLUSION RISKS AND THOUGHTS
Page 61 and 62: SECURE KERNEL COMPLEXITY / ATTACK S
Page 63 and 64: VSM WITHOUT SECUREBOOT • What’s
Page 65: YOU HAVE QUESTIONS? I HOPEFULLY HAV

BATTLE OF SKM AND IUM

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