Security and Exploitation

Secure boot, Chain of Trust

• A secure boot architecture is a general concept with different implementations per chip vendor, platform requirements, etc based around the Chain of Trust methodology
  • Without an HSM, a physical device cannot be truly secure. If HW cannot authenticate and control boot software, an attacker can create their own malicious boot software for the device.
• eFuse
  • Anti-rollback
  • Efuse - Wikipedia
• Standard/proper crypto practices
  • Storage of secrets (eFuse, One Time Programmable memory (OTP), baked in silicon, hardware crypto engines + key store, etc)
  • Key generation practices
• Secure initialization concepts (sensitive info clearing, lockdown of dangerous devices, etc)
  • Each boot stage (BootROM, BootLoader 1, 2, etc) should clear any sensitive data that is not necessary for other stages and lock down/disable access to components/devices/HW that are not needed ASAP
• Secure the Windows boot process - Windows security | Microsoft Docs
• Secure Boot and Trusted Boot - Windows security | Microsoft Docs
• Secure Boot and Chain of Trust - KOAN (koansoftware.com)

Control Flow Integrity (CFI)

• Control Flow Integrity - Wikipedia
• Pointer signing
  • ARM Pointer Auth - LLVM
  • AARCH64 Pointer Auth - Linux Kernel
• Canaries/cookies - Wikipedia
• Checkpoint systems
• Shadow stack - Wikipedia
• Valid jump/code flow lookup tables

Core Software Vulnerabilities

Buffer Overflows

• Different usage/vulnerabilities that usually result from heap vs stack
• Memory massaging

Integer Bugs

• Overflow/underflow
• Off-by-one

ROP/JOP

• Defenses: (Reference: CFI)
• Return-oriented programming - Wikipedia
• Return-to-libc attack - Wikipedia
• Return to libc - Geeks for Geeks
• Jump-Oriented Programming - Grades Fixer
• NOP Slide

Pointer Use After Free (UAF)

TODO...

Type Confusion

TODO...

Race Conditions

TODO...

Improper Crypto Implementations

• Insecure handling of keys
• Insecure crypto operation usage

Sensitive Information Leak

• Crypto keys/material
• Authentication credentials/passwords
• Pointer leak
  • Can lead to ASLR defeat by revealing the randomized base address, allowing attackers to create ROP/JOP chains
• DMA controllers
  • Can read/write wherever it has access to. In other words, if the IO controller has unrestricted access (or poor restrictions), attackers can leverage it to read/leak sensitive information or inject data/code into other parts of the system.
• Insecure data
  • Unprotected/unsigned external input
    • User input
    • User files (images, documents, etc)
    • Serial bus
    • Network/socket
  • Unencrypted memory
• Indirect observations/side channels
  • Insecure compare functions (memcmp, strcmp, etc) vs const time compare
    • Timing attack - Wikipedia
      • The Wiki example (as of writing) for constant time compare uses boolean logic to update the result
        (result &= a == b)
        to return a true/false statement. You can, alternatively, use bitwise operations
        (result |= a ^ b)
        to test equality
        (equal if result == 0).
• Side channel attacks/power analysis
  • Observations can be used to infer/derive crypto secrets
• Defenses:
  • CPU workload randonmness/noise
  • Internal shielding to prevent electric noise leakage
• Youtube - RSA Power Analysis Side-Channel Attack - rhme2
• Youtube - Breaking AES with ChipWhisperer - Piece of scake (Side Channel Analysis 100)
• Speculative execution attacks
  • Defenses:
    • Retpoline: A Software Construct for Preventing Branch-Target-Injection - Google
    • Retpoline: A Branch Target Injection Mitigation - Intel
  • Meltdown - Wikipedia
  • Spectre - Wikipedia
  • Row Hammer - Wikipedia
  • Spoiler - Wikipedia
  • Zenbleed - lock.cmpxchg8b

Fault Injection/"Glitching"

• Defenses
  • (Reference: CFI)
  • Software read/write and compare redundancy
  • Software random delays and/or varying clock speed
  • Prefer halt/fault/infinite loop instead of NOP/NULL for padding out chunks of code/text
  • Default "closed" (locked out/unprivileged) state, reset/error out to closed/locked state
  • Phase Locked Loops (PLL's) can detect faults when it causes it to come out of locked state
  • Compare local clock to high frequency external clocks
  • Optical/Light Sensors in package can detect decapsulation
  • In-chip UVLO (undervoltage lockouts) or Brown-out Detection (BOD) circuitry
  • Turnable Replica Circuits (TRC's)
  • Dual CPU execution units and compare
• Youtube - Hardware Power Glitch Attack (Fault Injection) - rhme2 Fiesta (FI 100)
• Youtube - exide: Glitching For n00bs
• Youtube - Implementing Practical Electrical Glitching Attacks
• Youtube - REcon 2015 Glitching and Side Channel Analysis for All (Colin o Flynn)
• Software-Based Fault Injection Countermeasures (Part 2/3) – NCC Group Research
• Alternative Approaches for Fault Injection Countermeasures (Part 3/3) – NCC Group Research

Additional References

• Youtube - Guarding Against Physical Attacks: The Xbox One Story - Tony Chen, Microsoft

Reverse Engineering

• Binary reversing
  • Getting familiar with standard tools (Ghidra, IDA, Hopper, etc)
  • Techniques/tricks/tools that help with reversing like decompiler, analysis, debugging, etc
  • Obfuscation techniques
    • TODO...
• Basic board design
  • Component identification
  • Identifying chips and what their role may be
• Extracting binaries
  • Exploit => injected code => serial/com channel
  • Intercepting traffic from insecure com channel
  • Dumping flash chips

Security Automation Tooling

• Automation tooling is not a fast fix solution. While blindly throwing tools at software can yield some results, the best results come from consideration of threat models, high-risk software components, pros-cons of different automation tools, etc in order to precisely test the security promises and entry points of the system.
• Static analysis
• Undefined behavior sanitizer (UBSan, etc)
• Fuzzing
• Emulation

Exploit/Rootkit Development

• Identifying potential entry points
  • Protocol/peripheral exploitation (USB, network stack, etc)
  • Custom/patched firmware
    • Running custom/unsigned FW (non-secure boot, glitching, etc)
    • Runtime patching vs persistent file patching
  • Malicious/crafted files/payloads
  • User space application/web browser vulnerabilities
    • Insecure deserialization
    • XML External Entities (XXE)
  • External web service vulnerabilities
    • XSS
    • Payloads/files from compromised services
• Chaining vulnerabilities in different software components to traverse the system/elevate privileges

Attestation

• Attestation concepts
• Evading detections/forging attestation responses