Re: [MORG] Review of draft-ietf-morg-fuzzy-search-02.txt

[Barry Leiba <[e-mail]>]

> Mentioning buffer overflows sound like they could be a bit too
> implementation specific.

I agree.  Moreover, I don't think it's the place of the IETF to tell
programmers how to program, and buffer overflow bugs are well enough
known that programmers should already know that they need to watch for
them.  I really don't think this opens things up for any more or
different buffer overflow bugs than any other spec does.

> Implementation of this extension might enable a denial-of-service attack
> if the implementation isn't careful to prevent them. Fuzzy search
> engines are often complex with non-obvious disk space, memory and/or CPU
> usage patterns. Implementors should test at least the behavior of large
> messages that contain very long words and/or unique random strings. Also
> very long search keys might cause excessive memory or CPU usage.
>
> Invalid input may also be problematic. For example if the search engine
> takes UTF-8 stream as input, it might fail more or less badly when
> illegal UTF-8 sequences are fed to it from a message whose character set
> was claimed to be UTF-8. This could be avoided by validating all the
> input and replacing illegal UTF-8 sequences with the Unicode replacement
> character (U+FFFD).
>
> Search relevancy rankings might be susceptible to "poisoning" by smart
> attackers using certain keywords or hidden markup (e.g. HTML) in their
> messages to boost the rankings. This can't be fully prevented by
> servers, so clients should prepare for it by at least allowing user to
> see all the  search results, rather than hide results below a certain
> score.

I'm happy with that text.

Barry