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109 lines
3.6 KiB
Markdown
109 lines
3.6 KiB
Markdown
# CSE4303 Introduction to Computer Security (Lecture 2)
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[Configuring VM](https://github.com/seed-labs/seed-labs/blob/master/manuals/vm/seedvm-from-scratch.md)
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## Course introduction and security fundamentals
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### Other security goals
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Authenticity: identity of an entity (issuer of info/message) is verified
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Anonymity: identity of an entity remains unknown
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Non-repudiation: messages can’t be denied or taken back (e.g. online transaction commitments)
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### Security foundations
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Security is about people, processes, technology
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- need all 3 to be secure!
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Security is about *trust in* people, processes, technology
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- Fundamental question: where is trust being placed, and is it justified?
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- Computing stack: compromise at a given level can impact any higher level
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Attackers often exploit assumptions
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"I assumed everyone would log out when they leave”
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"I didn’t expect anyone to do that"
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The assumptions we make are often hidden or implicit, making them easy to forget when reasoning about security of a system
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Reasoning about security requires properly defining security relative to the particular system:
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- What assets are being secured?
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- What properties should the system enforce?
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- CIA triad, anonymity, non-repudiation
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- What capabilities does the threat have?
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- Where does the system place trust?
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- What assumptions are being made?
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### Modeling attacks
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Common components:
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- System being attacked
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- Architecture of the system, trust model, assumptions, assets
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- Threat model
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- Attack surface: what can be attacked
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- Open ports and exposed services
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- Public APIs and their parameters
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- Web endpoints, forms, cookies
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- File system permissions
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- Hardware interfaces (USB, JTAG)
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- User roles and privilege boundaries
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- Attack vector: how the attacker attacks
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- SQL injection via POST /login
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- Phishing to steal credentials, then SSH login
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- Buffer overflow in a network daemon
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- Cross-site scripting through a comment field
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- Supply-chain poisoning of a dependency
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- Vulnerability: what the attacker can do
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- Exploit: how the attacker exploits the vulnerability
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- Damage: what the attacker can do
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- Mitigation: mitigate vulnerability
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- Defense: close vulnerability gap
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<details>
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<summary>Example</summary>
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Stealing credit card info via hidden scanner ("skimming")
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- System being attacked: card-swipe payment kiosk (alternative models?)
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- Threat model: professional criminal gang with substantial knowledge and resources
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- Attack surface: magstripe scanner
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- Attack vector: rogue scanner inserted into machine (e.g. at pay-at-the-pump gas station), or on top of existing scanner
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- Vulnerability: physical scanner easy(ish) to remove, and magstripes easy to read
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- Exploit: record card info as it’s scanned, then store/exfiltrate
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- Mitigation: 2FA in addition to magstripe (chip, PIN, zip code, etc.)
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- Defense: anti-tamper strips on card swiper
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</details>
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Importance of correct modeling
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- Attack-surface awareness guides defenses
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- E.g. pre-Covid-19 vs. post-Covid attack surface of company
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servers
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- Match resources to expected threat actors
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- Common threat actors
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- "Script kiddie": individual or group running off-the-shelf attacks
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- Caveat: off-the-shelf attacks can still be quite powerful! Metasploit, Shodan, dark web market.
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- "Insider attack": employee with access to internal machines/networks
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- "Advanced Persistent Threat (APT)": nation-state level
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resources and patience
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- All these threats have different motivations, require different defenses/responses!
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### Specific vulnerabilities
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Goal of the course: exposure to common threats in broad range of areas of computing stack
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- Hardware
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- OSes
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- Networks
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- Apps: web, AI/ML
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Studio time!
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