T1420Not expressible in SigmaMOBILE

File and Directory Discovery

DiscoveryAndroid, iOS

Where this stands

No Sigma rule can address this — the telemetry MITRE names has no Sigma logsource behind it.

Sigma has no logsource taxonomy for mobile platforms. MITRE's telemetry here is mobile EDR and device APIs, which no Sigma rule can address.

What the technique is

Adversaries may enumerate files and directories or search in specific device locations for desired information within a filesystem. Adversaries may use the information from File and Directory Discovery during automated discovery to shape follow-on behaviors, including deciding if the adversary should fully infect the target and/or attempt specific actions. On Android, Linux file permissions and SELinux policies typically stringently restrict what can be accessed by apps without taking advantage of a privilege escalation exploit. The contents of the external storage directory are generally visible, which could present concerns if sensitive data is inappropriately stored there. iOS's security architecture generally restricts the ability to perform any type of File and Directory Discovery without use of escalated privileges.

Read it on attack.mitre.org

What MITRE says you would watch

AN1788
Defender observes an app (package/UID) issuing high-rate directory or content-index enumerations against external/shared storage or other apps’ Documents/Media providers (logcat:ContentResolver, logcat:StorageAccessFramework), followed within a short window by bulk READ handles or stat/list calls over many distinct paths (logcat:FileIO). Activity occurs without foreground UI or exceeds typical per-app baseline, indicating automated file/dir discovery rather than user-driven browsing. Correlate on package/UID/profile and time proximity.
AN1789
Defender observes an app (bundle/process) performing large-scope directory listings or metadata reads via FileProvider/NSFileManager against user-visible containers (Files app locations, iCloud/On-My-iPhone) or external providers, with rapid traversal across many folders while the app is backgrounded or without corresponding UI activity (unifiedlogs:FileProvider, unifiedlogs:FileIO). Optional signals include Photo library or document picker bulk enumeration absent recent user gesture. Correlate on bundle/process/profile and path volume within a bounded window.