Outline for March 12, 2003
Reading: text, §22.1-22.5, 22.7, §18
Here's a little quiz to inspire you when you study for the final
(answers are below the outline -- try it before you look!).
- How long did the Hundred Years War last?
- In which country are Panama hats made?
- Where does catgut come from?
- What is a camel's hair brush made of?
- What kind of creatures were the Canary Isles named after?
- What was King George VI's first name?
- What color is a purple finch?
There! Wasn't that easy?
Outline for the Day
- Malicious logic
- Quickly review Trojan horses, viruses, bacteria; include animal and
Thompson's compiler trick
- Logic Bombs, Worms (Schoch and Hupp)
- Ideal: program to detect malicious logic
- Can be shown: not possible to be precise in most general case
- Can detect all such programs if willing to accept false positives
- Can constrain case enough to locate specific malicious logic
- Can use: writing, structural detection (patterns in code), common
code analyzers, coding style analyzers, instruction analysis
(duplicating OS), dynamic analysis (run it in controlled environment and
- Best approach: data, instruction typing
- On creation, it's type "data"
- Trusted certifier must move it to type "executable"
- Duff's idea: executable bit is "certified as executable"
and must be set by trusted user
- Practise: Trust
- Untrusted software: what is it, example (USENET)
- Check source, programs (what to look for); C examples
- Limit who has access to what; least privilege
- Your environment (how do you know what you're executing); UNIX examples
- Practise: detecting writing
- Integrity check files a la binaudit, tripwire; go through signature block
- LOCUS approach: encipher program, decipher as you execute.
- Co-processors: checksum each sequence of instructions, compute
checksum as you go; on difference, complain
- Sandboxes: confine protection domain of process
- Trust and assurance
- Policy, design, implementation, operational assurance
- Quick review of life cycle
And Their Answers
- 116 years (from 1337 to 1453).
- From sheep and horses.
- Squirrel fur.
- A large breed of dogs. The Latin name was
Insularia Canaria - "Island of Dogs."
- Albert. When he came to the throne in 1936 he respected
the wish of Queen Victoria that no future king should be called Albert.
- The distinctively colored parts are crimson.
Courtesy of Peter Langston via the YUCKS digest.
Here is a PDF version of this document.