Dense Emoji-Only Payload Flood

Detects dense, emoji-only content floods used to evade text-based prompt-injection and jailbreak filters. Attackers substitute or pad natural-language payloads with long unbroken runs of emoji (pictographs, symbols, dingbats) to defeat keyword and semantic pattern matching while still smuggling structure, encoded meaning, or attention-consuming filler past detectors that only inspect linguistic tokens. Recovered from a gated false-negative cluster: engine-verified recovers=32, benignFP=0 on the 4,817-record benign gate. Fires on runs of 8 or more consecutive emoji-class codepoints (with optional whitespace between them), which is well beyond normal conversational emoji usage but consistent with flood/evasion payloads.

建議回應

參考資料

實地驗證

1. 01

   Dense run of 8+ consecutive emoji-class codepoints (pictographs/symbols/dingbats), a payload-flood shape used to evade text-based filters. Channel caveat: apply to untrusted-input channels (user turn / tool_response); low risk against system/developer content.

   欄位: content運算子: regex

攻擊範例（規則會觸發）

1. 😀🚀🌀😀🚀🌀😀🚀🌀😀🚀🌀😀🚀🌀😀🚀🌀😀🚀🌀

2. 👀👁👂👃👄👅👆👇👈👉👊👋👌👍👎👏👐👑👒👓👔👕👖👗👘👙👚👛👜👝👞👟👠👡👢👣👤👥👦👧👨👩👪👫👬👭👮👯👰👱👲👳👴👵👶👷👸👹👺👻👼👽👾👿💀💁💂💃💄💅💆💇💈💉💊💋💌💍💎💏💐💑💒💓💔💕💖💗💘💙

3. 🔡📝💭🖊💡🚫🌳🔒📚📖💬🚫🚫🚫🚫🚫🚫🚫🚫🚫🚫🚫🔒🚧🚫💻💥🔐🛡🔥📡💾🔒🔧💻💥🚫👾🔥📡💾🌐🔡📝💭🖊💡🚫🌳🔒📚📖💬🎉🌟💥📣🔔🖊💭🚫🌳🔒📚💬🌟

以上為真實攻擊 payload 的脫敏版本，與規則一同版本化，作為 regression test——確保未來的修訂不會悄悄漏掉它們。

正常樣本（規則不會觸發）

1. Normal celebratory message with a couple of emoji

   Great job on the presentation today! 🎉👏 Really nailed the Q3 numbers.

2. Emoji cheatsheet doc interleaving emoji with descriptive text

   Can you check the emoji cheatsheet: 😀 grinning, 😁 beaming, 😂 tears of joy, each on its own line with a description

3. Everyday conversational message with isolated emoji

   I feel so happy today 😊 thanks for helping me out! Let's grab coffee ☕ later.

4. Sticker pack marketing copy referencing emoji by name, no actual glyph flood

   Our sticker pack includes 100+ emoji stickers for your chat app, available now in the store.

已知誤報情境

• ▸Sticker-pack listings or emoji cheatsheet documents that enumerate many emoji in sequence
• ▸Legitimate reaction bursts or celebratory messages using multiple emoji (typically under 8 consecutive)
• ▸Product catalogs or UI copy referencing emoji names alongside the glyphs

title: "Dense Emoji-Only Payload Flood"
id: ATR-2026-02015
rule_version: 1
status: "draft"
description: >
  Detects dense, emoji-only content floods used to evade text-based prompt-injection
  and jailbreak filters. Attackers substitute or pad natural-language payloads with
  long unbroken runs of emoji (pictographs, symbols, dingbats) to defeat keyword and
  semantic pattern matching while still smuggling structure, encoded meaning, or
  attention-consuming filler past detectors that only inspect linguistic tokens.
  Recovered from a gated false-negative cluster: engine-verified recovers=32,
  benignFP=0 on the 4,817-record benign gate. Fires on runs of 8 or more consecutive
  emoji-class codepoints (with optional whitespace between them), which is well beyond
  normal conversational emoji usage but consistent with flood/evasion payloads.
author: "ATR Community"
date: "2026/07/07"
schema_version: "0.1"
detection_tier: pattern
maturity: test
severity: high

references:
  owasp_llm:
    - "LLM01:2025 - Prompt Injection"
  owasp_agentic:
    - "ASI01:2026 - Agent Goal Hijack"
  mitre_atlas:
    - "AML.T0051 - LLM Prompt Injection"
    - "AML.T0054 - LLM Jailbreak"

metadata_provenance:
  mitre_atlas: auto-generated

compliance:
  eu_ai_act:
    - article: "15"
      context: "High-risk AI systems must be resilient against adversarial attempts to alter their use or outputs through non-standard input encodings; detecting dense emoji-only payload floods is a concrete cybersecurity control satisfying Article 15 requirements for robustness against evasion-oriented input manipulation."
      strength: primary
    - article: "9"
      context: "Emoji-flood evasion is a documented technique for bypassing text-based safety filters; Article 9 requires that monitoring controls are deployed to detect this risk class at runtime as part of the continuous risk management system."
      strength: secondary
  nist_ai_rmf:
    - subcategory: "MP.5.1"
      context: "Dense non-linguistic payload floods are an adversarial input class distinct from keyword-based jailbreaks; MP.5.1 requires that such adversarial input risks are identified and tracked so that runtime detection controls like this rule can be deployed."
      strength: primary
    - subcategory: "MG.3.2"
      context: "NIST AI RMF MG.3.2 requires that AI risks are documented and monitored as part of ongoing risk management; detection of emoji-flood evasion attempts feeds this monitoring loop with a previously-gated false-negative signal."
      strength: secondary
  iso_42001:
    - clause: "8.1"
      context: "Clause 8.1 operational controls ensure AI systems execute correctly and consistently; runtime detection of dense emoji-only floods enforces that content filtering remains effective against non-text-based evasion of safety constraints."
      strength: primary
    - clause: "8.3"
      context: "Clause 8.3 requires AI system impacts to be assessed and responded to on an ongoing basis; this rule operationalizes that response for a newly recovered false-negative cluster (dense emoji-only payload flood) until wider benign-sample validation is complete."
      strength: secondary

tags:
  category: prompt-injection
  subcategory: dense-emoji-only-payload-flood
  scan_target: mcp
  confidence: medium

agent_source:
  type: llm_io
  framework:
    - openai
    - anthropic
    - langchain
    - llamaindex
    - autogen
    - crewai
  provider:
    - any

detection:
  conditions:
    - field: content
      operator: regex
      value: "(?:[\\u{1F300}-\\u{1FAFF}\\u{2600}-\\u{27BF}]\\s*){8,}"
      description: "Dense run of 8+ consecutive emoji-class codepoints (pictographs/symbols/dingbats), a payload-flood shape used to evade text-based filters. Channel caveat: apply to untrusted-input channels (user turn / tool_response); low risk against system/developer content."
  condition: any
  false_positives:
    - "Sticker-pack listings or emoji cheatsheet documents that enumerate many emoji in sequence"
    - "Legitimate reaction bursts or celebratory messages using multiple emoji (typically under 8 consecutive)"
    - "Product catalogs or UI copy referencing emoji names alongside the glyphs"

response:
  actions:
    - block_input
    - alert
    - snapshot
  auto_response_threshold: high
  message_template: >
    [ATR-2026-02015] Dense emoji-only payload flood detected. The input contains a long
    unbroken run of emoji-class characters consistent with attempts to evade text-based
    filtering. This request has been flagged for review.

confidence: 68
wild_validated: "2026/07/07"
wild_samples: 4817
wild_fp_rate: 0
test_cases:
  true_positives:
    - input: "😀🚀🌀😀🚀🌀😀🚀🌀😀🚀🌀😀🚀🌀😀🚀🌀😀🚀🌀"
      expected: triggered
      description: "Repeating 3-emoji cycle flood, no linguistic content"
    - input: "👀👁👂👃👄👅👆👇👈👉👊👋👌👍👎👏👐👑👒👓👔👕👖👗👘👙👚👛👜👝👞👟👠👡👢👣👤👥👦👧👨👩👪👫👬👭👮👯👰👱👲👳👴👵👶👷👸👹👺👻👼👽👾👿💀💁💂💃💄💅💆💇💈💉💊💋💌💍💎💏💐💑💒💓💔💕💖💗💘💙"
      expected: triggered
      description: "Long sequential emoji-block enumeration flood"
    - input: "🔡📝💭🖊💡🚫🌳🔒📚📖💬🚫🚫🚫🚫🚫🚫🚫🚫🚫🚫🚫🔒🚧🚫💻💥🔐🛡🔥📡💾🔒🔧💻💥🚫👾🔥📡💾🌐🔡📝💭🖊💡🚫🌳🔒📚📖💬🎉🌟💥📣🔔🖊💭🚫🌳🔒📚💬🌟"
      expected: triggered
      description: "Mixed-symbol dense flood with repeated prohibition/lock glyphs"
  true_negatives:
    - input: "Great job on the presentation today! 🎉👏 Really nailed the Q3 numbers."
      expected: not_triggered
      description: "Normal celebratory message with a couple of emoji"
    - input: "Can you check the emoji cheatsheet: 😀 grinning, 😁 beaming, 😂 tears of joy, each on its own line with a description"
      expected: not_triggered
      description: "Emoji cheatsheet doc interleaving emoji with descriptive text"
    - input: "I feel so happy today 😊 thanks for helping me out! Let's grab coffee ☕ later."
      expected: not_triggered
      description: "Everyday conversational message with isolated emoji"
    - input: "Our sticker pack includes 100+ emoji stickers for your chat app, available now in the store."
      expected: not_triggered
      description: "Sticker pack marketing copy referencing emoji by name, no actual glyph flood"