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Abuse filters can be fooled by using U+200B ZERO WIDTH SPACE (ccnorm doesn't remove/normalize them)
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As you can check on
where the first string has just 3 characters and the second one has a few invisible characters inside it.

Therefore, anyone can fool abuse filters which try to avoid ofenses, badwords, etc.. by just copying invisible characters in the text.

Version: unspecified
Severity: normal



Event Timeline

bzimport raised the priority of this task from to Normal.Nov 22 2014, 3:03 AM
bzimport added a project: AntiSpoof.
bzimport set Reference to bz62049.
bzimport added a subscriber: Unknown Object (MLST).
He7d3r created this task.Feb 28 2014, 12:17 PM
hoo added a comment.Feb 28 2014, 12:20 PM

To fix this, we would either need to add these characters to AntiSpoof's maintenance/ (and make them normalize to and empty string) or, if that's not possible/ desired, we could also extend our own ccnorm function.

Seems like antispoof would be the right place for this.

Change 117640 had a related patch set uploaded by Hoo man:
Map U+200B (zero width space) to an empty string

Change 117640 merged by jenkins-bot:
Map U+200B (zero width space) to an empty string

hoo added a comment.Mar 12 2014, 11:38 PM

Chris approved my patch