Topic 2

Question 1

What is Un-validated Input?

Answer 1

Input received by program from untrusted source is a potential target for attack.

Question 2

Possible threats of Unvalidated Input?

Answer 2

**– Buffer Overflows **- input that has been designed to overwrite program execution space
**– Cross Site Scripting ** input that contains scripts to be executed on other user’s browsers
– Command Injection - input that is modified to contain executable commands

Question 3

How to validate all inputs?

Answer 3

• Limit maximum input character length
• Numbers: check bounds - min & max
• Make sure encodings (e.g. UTF-8, URL encoding) are legal and decoded results are legal
• Aware of various data types and input sources – Watch out for special characters (e.g. ‘, <, >)

Question 4

What is Stack?

Answer 4

– Memory is allocated for automatic (local) variables within functions its used for temporary storage of information.
– Last In First Out (LIFO)

Question 5

What is Heap?

Answer 5

– Memory allocated in the heap remains in existence for the duration of a program. It is used for dynamic memory allocation

Question 6

What is Stack and Heap?

Answer 6

– Memory space for objects is always allocated in heap. Variables are placed on stack.

Question 7

Benefits of threat modelling

Answer 7

• Discovers system threats before coding
• Saves cost as flaws are addressed during design time
• Validate the architecture and design
• Contribute to the risk management and Attack Surface Reduction process
• Guide the code review process and penetration testing process

Question 8

Security Principles

Answer 8

• Minimize your attack surface
• Employ secure defaults
• Assume external systems are insecure
• Fail safely
• Never rely on security through obscurity alone

Question 9

Purpose of threat modelling

Answer 9

1. Understand security threats to a system
2. Determine risks from those threats
3. Establish appropriate mitigations