Leetspeak
Substituting digits and symbols for visually similar letters — 3 for e, 1 or ! for i/l, 4 or @ for a, 0 for o — as in h4rm3l. Models read it fluently; naive matchers do not. It is trivially cheap, composes with every other transformation, and remains one of the axes where detectors most often turn out to have been overfit to the exact spellings they were tuned on.
See also h4rm3l · homoglyph · normalization pre-pass
Related terms
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h4rm3l
Attack families
A family built around composable string transformations: a small language of primitives — character substitution, insertion, role framing, encoding — that…
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Homoglyph
Attack concepts
A character that looks identical or near-identical to another but has a different Unicode code point — Cyrillic а for Latin a, Greek ο for o, a full-width…
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Normalization pre-pass
MoorAI terms
A bounded decode-and-fold stage that runs before the detectors: strip zero-width and bidirectional control characters, fold homoglyphs and leetspeak…
Attack concepts
The mechanisms the families above exploit, plus the agent-specific ones that have no chatbot equivalent. If you only read one entry on this page, read indirect prompt injection.