Suspicious Error 524 Decoy Smishing Phishing Endpoint Access (via proxy)
- Category
- proxy
- Author
- HuntRule
- Published
- 2026-06-22
- Updated
- 2026-08-28
ATT&CK techniques
Initial Access → ExfiltrationRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
Exfiltration
Impact
What it detects
This rule detects access to the single-page phishing endpoints used by the Error 524 decoy smishing campaign, including getApp application-id lookups and WebSocket uuid exfiltration paths. The campaign hides credential and card data theft behind fake Cloudflare Error 524 pages. Detecting these URIs reveals victims interacting with the phishing infrastructure.
Reporting behind it
- group-ib.comhttps://www.group-ib.com/blog/error-524-decoy-smishing/
- attack.mitre.orghttps://attack.mitre.org/techniques/T1566/002/
- attack.mitre.orghttps://attack.mitre.org/techniques/T1071/001/
- attack.mitre.orghttps://attack.mitre.org/techniques/T1041/
- group-ib.comhttps://www.group-ib.com/blog/error-524-decoy-smishing-es/
- attack.mitre.orghttps://attack.mitre.org/techniques/T1656/
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
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