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Embedded System
- Microprocessor used as a component in a device
and is designed for a specific control function within a device
- Used In:
- Cell Phones
- Household appliances
- Camera
- And more
Embedded System Security Professor Patrick McDaniel Charles Sestito - - PowerPoint PPT Presentation
Embedded System Security Professor Patrick McDaniel Charles Sestito - - PowerPoint PPT Presentation
Embedded System Security Professor Patrick McDaniel Charles Sestito Fall 2015 Embedded System Microprocessor used as a component in a device and is designed for a specific control function within a device Used In: Cell Phones
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Requirements
- Low cost
- Fast
- Fit within hardware and software constraints
- Size (must be small)
- Reliable
- Reactive
- Real-time
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Attacks on systems
- Many different types of attacks
- Embedded Software Attacks
- Physical Attacks
- Logical Attacks
- Timing Analysis
- Power Analysis
- Fault Induction
- Electromagnetic Analysis
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Embedded Software Attack
- Three factors that contribute to security risks in
embedded software
- Complexity
- Extensibility
- Connectivity
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Complexity
- Software is complicated
- The more complex the code, the more possibly
bugs and vulnerabilities
- Unsafe programming language
- C++ is very common
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Extensibility
- Modern systems are designed to be extended
- Updates
- Extensions
- Loadable device driver and modules must be
accounted for
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Connectivity
- Some embedded systems are being connected to
the internet
- Even more so with IoT
- Possible small failures could lead to security
breaches
- Attacker can use series of automated attacks
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Physical Attack
- Eavesdropping
- Probes listen in on inter-component communications
- Micro-probing
- Use normal communication interface and abuse security
vulnerabilities
- De-packaging
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De-Packaging
- Use fuming acid to dissolve resin covering silicon
- f a chip package
- Recontruct the layout using a systematic
combination of microscopy and invasive removal
- f covering layers
- Internals of the chip can be inferred
- Can obtain ALU, ROM cells, instruction decode, and
more in detailed view with this technique
- Microprobe to observe interfaces between
components
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Logical Attack
- Send messages to device, observe response
- Trick device into revealing the key
- Exploits design flaws
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Timing Analysis
- Keys can be determined by analyzing small
variations in the time required to perform cryptographic computations
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Power Analysis
- Operating current drawn by hardware is correlated
to computations being performed
- In most IC’s, logic gates and losses due to
parasitic capacitance are major contributors to power consumption
- Two types
- Single power analysis
- Differential Power analysis
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Fault Induction
- Security isn’t only software dependant
- Hardware failing to make proper computations is a
security vulnerability
- RSA implementation can be compromised if any
computation errors
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Electromagnetic Analysis
- Documented since the 80’s
- Measures electromagnetic radiation emitted by
device to reveal sensitive information
- Success deployment requires knowledge of chip
layour
- Two types
- Simpler EMA (SEMA)
- Differential EMA (DEMA)
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Design challenged
- Processing Gap
- Battery Gap
- Flexibility
- Tamper Resistance
- Assurance Gap
- Cost
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Processing Gap
- Some systems are not capable of keeping up with
computational demands of security processing
- Increase data rates and complexity of security protocols
- Processing gap is obvious in systems which need
to process high data rates
- Network routers, firewalls, web servers
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Battery Gap
- Battery capacity increases at an average of 5-8%
per year
- Security processing energy requirements outpace
the increase in battery capacitance
- Leads to battery gap
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Flexibility
- Embedded systems often required to execute
multiple and diverse security protocols
- Need to be able to support
- Multiple security
- Interoperability in different environments
- Security processing in different layers of the network
protocol stack
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Tamper Resistance
- Attacks due to malicious software
- Most common
- Viruses
- Trojan Horses
- Can exploit OS vulnerabilites
- Disrupt normal functioning
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Assurance Gap
- Truly reliable systems are much more difficult to
build
- Reliable systems must be able to handle wide
range of situations
- Secure systems should be able to operate despite
attacks
- Increase in complexity makes it more difficult to
realize if something was overlooked
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Cost
- Fundamental factor that influences the security
architecture
- Increase in security leads to increase in cost
- Designer’s responsibility to balance security cost
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Security Levels
- Level 1
- Requires minimal physical protections
- Level 2
- Requires addition of tamper-evident mechanisms
- Seal or enclosure
- Level 3
- Stronger detection and response mechanisms
- Level 4
- Mandates environmental failure protection and testing
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Countermeausres
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Software Security
- Best approach is to think about security early on
- Software security should be applied at various
levels
- Requirements level
- Design level
- Code level
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Physical Attacks
- Hard to use because of chip size, smaller = better
- Expensive compared to other attacks
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Logic Attacks
- Logical attack countermeasures
- Ensure privacy and integrity sensitive code and data
- Determine that it is safe from a security standpoint to
execute a program
- Identify and remove software bugs and design flaws
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Timing Analysis
- Obvious countermeasures don’t work
- Quantizing total time
- Adding random delays
- Message blinding can be used with RSA
- Make all computations the exact same time
- Other public=ley cryptosystems
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Power Analysis
- Run other circuits simultaneously
- Doesn’t prevent attack but attacker needs more samples
- Effective countermeasures are mathematically
rigorous and non-intuitive
- Effective countermeasure remain expensive and
challenging
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Fault Induction
- RSA implementations can check their answers by
performing a public-key operation
- Many cryptographic devices include an assortment
- f glitch sensors
- Detect condition likely to cause computation errors
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Work Cited
- Adapted from Dr. Mohammad Tehranipoor slides