{"success":true,"data":{"id":"subject-invisible-char-obfuscation","label":"Zero-width char hidden inside subject keyword","description":"The subject line contains a zero-width or word-joiner character (U+200B ZWSP, U+200C ZWNJ, U+200D ZWJ, U+200E/F LTR/RTL marks, U+2060 word joiner, U+FEFF BOM) positioned between two ASCII letters. Subject-level sibling of the body zero-width obfuscation signal (iter 425). The attacker inserts an invisible char inside a scam keyword (`p​assword reset`, `w‍ire t‍ransfer`, `ver⁠ify`) so that literal-string keyword filters and search indexes don't match while the rendered subject reads normally. The \"between two ASCII letters\" constraint prevents false positives on legitimate emoji ZWJ sequences, Arabic/Indic renderer glue, and stray BOMs — no legitimate English/Latin word ever has an invisible char between two ASCII letters. Weighted at +4 — higher than the body variant (+3) because the subject has essentially zero legitimate use of invisible chars and every subject character is deliberate.","tier":"danger","category":"subject","isThin":false}}