detecting-qr-code-phishing-with-email-security

name	detecting-qr-code-phishing-with-email-security
description	Detect and prevent QR code phishing (quishing) attacks that embed malicious URLs inside QR code images to bypass link-based email security, using image-based threat detection, OCR/QR decoding, and mobile-side scanning (Microsoft Defender for O365, Proofpoint TAP, Barracuda Multimodal AI). Use when configuring gateway rules against QR phishing or investigating suspicious emails containing QR codes.
domain	cybersecurity
subdomain	phishing-defense
tags	["quishing","qr-code","phishing","email-security","image-analysis","ocr","mobile-security"]
version	1.0
author	mahipal
license	Apache-2.0
atlas_techniques	["AML.T0052","AML.T0024","AML.T0035"]
nist_ai_rmf	["MEASURE-2.8","MAP-5.1"]
nist_csf	["PR.AT-01","DE.CM-09","RS.CO-02","DE.AE-02"]
mitre_attack	["T1566","T1598","T1534","T1036","T1027"]
mitre_f3	{"version":"1.1","tactics":["reconnaissance","resource-development","initial-access"],"techniques":[{"id":"T1598","name":"Phishing for Information","tactic":"reconnaissance","source":"attack"},{"id":"T1660","name":"Phishing","tactic":"initial-access","source":"attack"},{"id":"F1020.002","name":"Create Fake Materials: Fake Website","tactic":"resource-development","source":"f3"},{"id":"T1583.001","name":"Acquire Infrastructure: Domains","tactic":"resource-development","source":"attack"},{"id":"F1006.002","name":"Account Takeover: Exposed Login Credential","tactic":"initial-access","source":"f3"}]}

Detecting QR Code Phishing with Email Security

Overview

QR code phishing (quishing) is a rapidly growing attack vector where malicious URLs are embedded in QR code images within phishing emails. Quishing incidents grew fivefold from 46,000 to 250,000 between August and November 2025, with credential phishing comprising 89.3% of detected incidents. Traditional email security filters struggle because QR codes cannot be read by humans or standard URL scanners, and when scanned, users typically use personal mobile devices that lack corporate security controls. Attackers have evolved to use split QR codes (two separate images), nested QR codes, and ASCII text-based QR codes to evade detection.

When to Use

• When investigating security incidents that require detecting qr code phishing with email security
• When building detection rules or threat hunting queries for this domain
• When SOC analysts need structured procedures for this analysis type
• When validating security monitoring coverage for related attack techniques

Prerequisites

• Email security gateway with image analysis capabilities
• Understanding of QR code structure and encoding
• Mobile device management (MDM) or mobile threat defense solution
• Security awareness training program
• SIEM platform for correlation and alerting

Key Concepts

Why Quishing Works

1. Bypasses URL Scanners: Traditional gateways scan text-based URLs but cannot decode image-embedded URLs
2. Shifts to Unprotected Devices: Corporate email arrives on secured systems but QR scan occurs on personal mobile devices
3. User Trust: QR codes are normalized in daily life (payments, menus, parking)
4. Low Detection Rate: Only 36% of quishing incidents are accurately identified by recipients

Evasion Techniques (2025)

• Split QR Codes: QR code divided into two separate images that look benign individually (Gabagool PhaaS kit)
• Nested QR Codes: QR code within a QR code, with first scan leading to intermediate page
• ASCII QR Codes: QR rendered as text characters instead of images, bypassing image analysis (12% of attacks in Jan 2026)
• Styled/Artistic QR Codes: Custom-designed QR codes with logos that evade pattern matching
• PDF Attachment QR: QR code embedded in PDF attachment rather than email body

Detection Challenges

• Pattern-based detection faces trade-off: aggressive tuning causes false positives, cautious tuning causes misses