Integer Vulnerabilities

Introductions

• introductions of two students

Questions on the readings

The readings today are from Computer Security and the Internet, Chapter 6, sections 6.2.

Key Concepts

Integer-based vulnerabilities

• understand C data types, unsigned and signed versions

  • see table 6.1
  • modern C uses uint16_t and int16_t
  • what happens if you convert types, e.g. through casting?

• understand two’s complement — see Table 6.3, page 164

• integer underflow and overflow

  • see Example on Integer overflow on multiplication

• see Table 6.2, page 163 for examples of integer vulnerabilities

• see the software consequences list, 1 through 4, page 163

• mitigations — compiler flags to catch integer errors, developer toolsets, safe integer library functions

• it would be great to switch to a better language (Rust!) but we have to live with what we have for now

Class Exercises

See the software security repo for code we will use:

• In integer we will run rectangular, which has an integer overflow problem, and waiting-list, which has an integer underflow problem.

Additional Materials

Reviewing Code for Integer Manipulation Vulnerabilities