Obfuscated Files or Information
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 attempt to make a payload or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the device or in transit. This is common behavior that can be used across different platforms and the network to evade defenses. Payloads may be compressed, archived, or encrypted in order to avoid detection. These payloads may be used during Initial Access or later to mitigate detection. Portions of files can also be encoded to hide the plaintext strings that would otherwise help defenders with discovery. Payloads may also be split into separate, seemingly benign files that only reveal malicious functionality when reassembled.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN1851
Defender correlates a sandboxed app writing high-entropy or encoded artifacts (often in app-private or shared storage), performing decode/decompress/reassembly, then dynamically loading/execing the resulting code (DexClassLoader/JNI dlopen) or spawning a helper process. Sequence: high-entropy file writes → decode/unpack bursts → new.dex/.so/.jar creation in temp/obfuscated paths → dynamic load or shell spawn within a tight window.
- AN1852
Defender correlates a sandboxed app downloading or receiving opaque/encoded blobs, writing high-entropy content into container/tmp, performing decode/decompress/reassembly, and then executing/loaded as Mach-O or bundle (dlopen) or leveraging JIT/RWX pages to run the decoded payload. Sequence: opaque download or IPC → high-entropy writes/split-file bursts → decode/unarchive → new Mach-O/bundle in tmp → dlopen/posix_spawn or RWX region activity.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.