JTAGulator: Assisted discovery of on-chip ... - Grand Idea Studio

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Agenda• Introduction• Inspiration / Other Art• Traditional HW RE Techniques• On-Chip Debug Interfaces• Design Requirements• Hardware• Firmware• Examples / Demonstration• Limitations• Future Work
Introduction• On-chip debug interfaces are a well-knownattack vector- Can provide chip-level control <strong>of</strong> a target device- Extract program code or data- Modify memory contents- Affect device operation on-the-fly- Gain insight into system operation• Inconvenient for vendor to remove functionality- Would prevent capability for legitimate personnel- Weak obfuscation instead (hidden or unmarkedsignals/connectors)- May be password protected (if supported by device)
Page 1: Assisted Discovery
Page 5 and 6: Goals• Create an easy-to-use tool
Page 7 and 8: Other Art• An Open JTAG Debugger
Page 9 and 10: HW Reverse Engineering• Informati
Page 11 and 12: Identifying Interfaces: Internal•
Page 13 and 14: Identifying Interfaces: Internal 3
Page 15 and 16: Manually Determining Pin Function
Page 17 and 18: On-Chip Debug Interfaces• JTAG•
Page 19 and 20: JTAG 2• Multiple devices can be "
Page 21 and 22: JTAG: Architecture 2
Page 23 and 24: JTAG: Instructions┌────
Page 25 and 26: JTAG: HW Tools• RIFF Box- www.jta
Page 27 and 28: UART• Universal Asynchronous Rece
Page 29 and 30: UART 3Mark (Idle)SpaceBit width= ~8
Page 31 and 32: Design Requirements• Open source/
Page 33 and 34: Development
Page 35 and 36: Assembly Drawing
Page 37 and 38: Schematic: Target InterfaceNOTE: RE
Page 39 and 40: Propeller/Core 2• Clock: DC to 12
Page 41 and 42: Propeller/Core 4• Standard develo
Page 43 and 44: USB Interface• Allows for Propell
Page 45 and 46: Adjustable Target Voltage• PWM fr
Page 47 and 48: Level Translation 2
Page 49 and 50: Input Protection 2• NUP4302MR6 Sc
Page 51 and 52: Firmware
Page 53 and 54:
Cogs• Spin Interpreter (Cog 0)•
Page 55 and 56:
General Commands• Set target syst
Page 57 and 58:
IDCODE Scan• 32-bit Device ID (if
Page 59 and 60:
IDCODE Scan 3• Ask user for numbe
Page 61 and 62:
BYPASS Scan 2• Can determine how
Page 63 and 64:
JTAG: Examples
Page 65 and 66:
Linksys WRT54G v1.1• Broadcom BCM
Page 67 and 68:
D-Link DWL-900AP+ 2• Lattice ispM
Page 69 and 70:
BlackBerry 7250• Qualcomm MSM6500
Page 71 and 72:
BlackBerry 7290 2
Page 73 and 74:
UART Scan• Ask user for desired o
Page 75 and 76:
UART Scan 3
Page 77 and 78:
Linksys WRT54G v2 rXH (w/ DD-WRT)
Page 79 and 80:
Scan Timing 2• UART- Only need to
Page 81 and 82:
Possible Limitations• Could cause
Page 83 and 84:
Other Uses• Propeller development
Page 85 and 86:
A Poem
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JTAGulator: Assisted discovery of on-chip ... - Grand Idea Studio

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