[Bug 3173] New: Bayes can be circumvented by faking invisible or near-invisible text.

[bu...@bugzilla.spamassassin.org]

http://bugzilla.spamassassin.org/show_bug.cgi?id=3173

           Summary: Bayes can be circumvented by faking invisible or near-
                    invisible text.
           Product: Spamassassin
           Version: SVN Trunk (Latest Devel Version)
          Platform: Other
        OS/Version: other
            Status: NEW
          Severity: normal
          Priority: P5
         Component: Learner
        AssignedTo: spamassassin-dev@incubator.apache.org
        ReportedBy: koppel@ece.lsu.edu


The fix associated with Bug 2129 would allow spammers to circumvent
Bayesian classification. (There is also discussion on this in Bug 2282.)

With the following changes,
  r9460 | jm | 2004-03-13 23:49:08 -0600 (Sat, 13 Mar 2004) | 1 line

a message could be crafted so that it would be considered not
"visible_for_bayes" but still visible enough when using a typical
email client.  That might be done by using a seemingly low contrast
color pair or by markup that tricks the code into thinking the text is
invisible (for example, using complex styles).

Such messages would get around one of the more robust spam detection
techniques used in SpamAssassin.  

As an alternative, tag invisible text, as suggested in Bug 2129.


With respect to Bug 2129 cmment 16,

> This bug has been marked as Resolved Fixed after the invisible text
> code was checked in and reduced FNs by 7% with no new FPs.

my concern is not with existing spam but with future messages designed
to take advantage of r9460.



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