Notes for December 7, 2000
- Greetings and Felicitations!
- Status of target
- Puzzle of 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
- Practise: detecting writing
- Integrity check files a la binaudit, tripwire; go through
- LOCUS approach: encipher program, decipher as you execute.
- Co-processors: checksum each sequence of instructions, compute
checksum as you go; on difference, complain
Puzzle of the Day
Consider this a warm-up for the final. Good luck!
Seven of the World's Easiest Questions
- 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?
The answers are on the web.
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
- The distinctively colored parts are crimson.
Courtesy of Peter Langston via the YUCKS digest.
Office: 3059 Engineering Unit II
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Copyright Matt Bishop, 2000.
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Page last modified on 12/8/2000