{"source_checked_on":"2026-10-19","schema_version":1,"key":"mobile/T1521","id":"T1521","name":"Encrypted Channel","domain":"mobile","reviewed_on":"2026-09-28","source_url":"https://attack.mitre.org/techniques/T1521","source_file":{"file":"mobile.json","url":"https://raw.githubusercontent.com/mitre-attack/attack-stix-data/20664a889568dce884a1dac0ec7b12ae3a199f51/mobile-attack/mobile-attack-20.0.json","sha256":"824f7d8a37e7893b29e4c6ca6d87b5fbbf3b228ec6384f1a69ee20d523ff59e5","bytes":6095145},"source_object_sha256":"d6ef0879faeffa80c80b0a47876122e22b733a8e16171ae20963f2ec45718f15","description":"Adversaries may explicitly employ a known encryption algorithm to conceal command and control traffic rather than relying on any inherent protections provided by a communication protocol. Despite the use of a secure algorithm, these implementations may be vulnerable to reverse engineering if necessary secret keys are encoded and/or generated within malware samples/configuration files.","references":[{"source_name":"mitre-attack","url":"https://attack.mitre.org/techniques/T1521","external_id":"T1521"}],"platforms":["Android","iOS"],"environments":["mobile"],"visibility":"source_mapped","visibility_note":null,"parent":null,"children":[{"key":"mobile/T1521.001","id":"T1521.001","name":"Symmetric Cryptography","page":"techniques/mobile/T1521.001/"},{"key":"mobile/T1521.002","id":"T1521.002","name":"Asymmetric Cryptography","page":"techniques/mobile/T1521.002/"},{"key":"mobile/T1521.003","id":"T1521.003","name":"SSL Pinning","page":"techniques/mobile/T1521.003/"}],"telemetry":[{"id":"DC0114","name":"Application Permission","page":"telemetry/DC0114/","kind":"attack_component","category":"Mobile lab instrumentation","description":"Declared or granted permissions of a mobile application.","collection_focus":"Compare manifest declarations with runtime granted state using authorized package inspection and own-app permission checks.","providers":[{"name":"Android logcat","scope":"Permitted logs from a consented test device/emulator; output depends on build, permissions and instrumentation.","source_id":"android_logs"},{"name":"Android dumpsys","scope":"Point-in-time service/package state on an authorized development device.","source_id":"android_state"},{"name":"Instrumented test application","scope":"Own-app permission, API and state callbacks; not universal visibility into other apps.","source_id":"android_permissions"}],"configuration":["Use a disposable emulator or owned development device with approved debugging. Record OS/API level, app version and instrumentation privileges.","Collect only relevant logcat buffers/tags and service snapshots; add explicit own-app instrumentation for events absent from OS logs.","Forward sanitized logs and compare before/after state. Remove test data and revoke debugging access after the lab session."],"configuration_example":{"label":"Inspect the owned Android lab application","language":"shell","source_id":"android_state","content":"adb shell dumpsys package test.example.lab","note":"Read-only snapshot on a consented debug device. Replace the example package with your owned test app. Output and access vary by Android build; this is not a permission-request event stream."},"required_fields":["package","permission","declared","granted"],"example":{"schema":"1200km.telemetry.example.v1","synthetic":true,"timestamp":"2026-09-27T12:00:00Z","telemetry_id":"DC0114","collector":"illustrative-lab-collector","observation":{"package":"test.example.lab","permission":"android.permission.CAMERA","declared":true,"granted":false}},"example_note":"Project-normalized synthetic JSON, not a native provider log, captured event, attack verdict or validated detection. A parser/adapter is required for a real SIEM. Example names, IPs and values are fictional.","limitations":"Android tooling does not imply iOS coverage. Standard mobile apps cannot observe all other apps or protected OS internals; MDM status is not full API, filesystem or content telemetry.","sources":[{"id":"android_logs","title":"Android logcat and access limits","url":"https://developer.android.com/tools/logcat"},{"id":"android_state","title":"Android dumpsys","url":"https://developer.android.com/tools/dumpsys"},{"id":"android_permissions","title":"Android runtime permission requests","url":"https://developer.android.com/training/permissions/requesting"}],"association":"attack_component","anomaly_design":"Per owned device, app version and permission state: unexpected API/permission changes, background activity and network destinations. OS privacy restrictions and emulator differences limit observability."},{"id":"DC0123","name":"Application State","page":"telemetry/DC0123/","kind":"attack_component","category":"Mobile lab instrumentation","description":"Application state and lifecycle observations such as foreground/background transitions.","collection_focus":"Instrument the owned app lifecycle and corroborate permitted service snapshots; distinguish app events from inferred gateway activity.","providers":[{"name":"Android logcat","scope":"Permitted logs from a consented test device/emulator; output depends on build, permissions and instrumentation.","source_id":"android_logs"},{"name":"Android dumpsys","scope":"Point-in-time service/package state on an authorized development device.","source_id":"android_state"},{"name":"Instrumented test application","scope":"Own-app permission, API and state callbacks; not universal visibility into other apps.","source_id":"android_permissions"}],"configuration":["Use a disposable emulator or owned development device with approved debugging. Record OS/API level, app version and instrumentation privileges.","Collect only relevant logcat buffers/tags and service snapshots; add explicit own-app instrumentation for events absent from OS logs.","Forward sanitized logs and compare before/after state. Remove test data and revoke debugging access after the lab session."],"configuration_example":null,"required_fields":["package","state_before","state_after","source"],"example":{"schema":"1200km.telemetry.example.v1","synthetic":true,"timestamp":"2026-09-27T12:00:00Z","telemetry_id":"DC0123","collector":"illustrative-lab-collector","observation":{"package":"test.example.lab","state_before":"background","state_after":"foreground","source":"own_app_callback"}},"example_note":"Project-normalized synthetic JSON, not a native provider log, captured event, attack verdict or validated detection. A parser/adapter is required for a real SIEM. Example names, IPs and values are fictional.","limitations":"Android tooling does not imply iOS coverage. Standard mobile apps cannot observe all other apps or protected OS internals; MDM status is not full API, filesystem or content telemetry.","sources":[{"id":"android_logs","title":"Android logcat and access limits","url":"https://developer.android.com/tools/logcat"},{"id":"android_state","title":"Android dumpsys","url":"https://developer.android.com/tools/dumpsys"},{"id":"android_permissions","title":"Android runtime permission requests","url":"https://developer.android.com/training/permissions/requesting"}],"association":"attack_component","anomaly_design":"Per owned device, app version and permission state: unexpected API/permission changes, background activity and network destinations. OS privacy restrictions and emulator differences limit observability."},{"id":"DC0039","name":"File Creation","page":"telemetry/DC0039/","kind":"attack_component","category":"Endpoint activity","description":"Creation or overwrite of a file at an observed path.","collection_focus":"Scope Sysmon FileCreate (11) to the lab directory; retain the process and file path. Differentiate creation/overwrite if the sensor can.","providers":[{"name":"Microsoft Sysmon","scope":"Windows event-based collection; enable the event types needed below.","source_id":"sysmon"},{"name":"Linux Audit","scope":"Linux alternative for supported system-call and file events; different semantics and fields.","source_id":"linux"},{"name":"Apple Endpoint Security clients","scope":"macOS alternative where the subscribed event exists; requires an entitled, approved client, not an iOS collector.","source_id":"apple"}],"configuration":["On a disposable Windows host, review the installed Sysmon schema and current configuration; merge scoped event filters into the existing policy rather than replacing it.","Forward Microsoft-Windows-Sysmon/Operational to the lab collector. Preserve event ID, timestamp, computer, process identifiers and the original event.","For Linux or macOS, select the equivalent sensor separately and test its emitted fields; a Windows event ID does not transfer across platforms."],"configuration_example":null,"required_fields":["process_id","path","action","size_bytes"],"example":{"schema":"1200km.telemetry.example.v1","synthetic":true,"timestamp":"2026-09-27T12:00:00Z","telemetry_id":"DC0039","collector":"illustrative-lab-collector","observation":{"process_id":4200,"path":"C:\\Lab\\demo.txt","action":"create","size_bytes":64}},"example_note":"Project-normalized synthetic JSON, not a native provider log, captured event, attack verdict or validated detection. A parser/adapter is required for a real SIEM. Example names, IPs and values are fictional.","limitations":"Event filtering and sensor versions change coverage. High-volume image-load and process-access collection needs tuning; endpoint events alone do not establish intent.","sources":[{"id":"sysmon","title":"Microsoft Sysmon events and configuration","url":"https://learn.microsoft.com/en-us/sysinternals/downloads/sysmon"},{"id":"sysmon_config","title":"Microsoft Sysmon configuration files","url":"https://learn.microsoft.com/en-us/windows/security/operating-system-security/sysmon/sysmon-configuration-files"},{"id":"linux","title":"Linux Audit rule configuration","url":"https://www.man7.org/linux/man-pages/man8/auditctl.8.html"},{"id":"apple","title":"Apple Endpoint Security framework for macOS","url":"https://developer.apple.com/documentation/endpointsecurity"},{"id":"process_audit","title":"Microsoft process creation event 4688","url":"https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/auditing/event-4688"}],"association":"attack_component","anomaly_design":"Per host role and user: rare process/object combinations, bursts of object access or modification, and ordered parent/action sequences. Compare maintenance windows and signed software rollout activity."},{"id":"DC0021","name":"OS API Execution","page":"telemetry/DC0021/","kind":"attack_component","category":"Application and service audit","description":"Instrumented operating-system API calls and their return values.","collection_focus":"Use an approved EDR trace or instrument the owned lab process at selected APIs. Define API name, caller, sanitized arguments and return status.","providers":[{"name":"Application audit logs","scope":"First-party service events and request/result fields; schema is application-specific.","source_id":"otel"},{"name":"OpenTelemetry-compatible log pipelines","scope":"Transport and normalization of emitted records; do not create missing audit instrumentation.","source_id":"otel"}],"configuration":["Enable the application audit category or instrument the owned lab application at the authorization/action boundary.","Define a schema with timestamp, service, actor, object, action, result and correlation ID. Export structured records through an authenticated collector.","Redact secrets and personal content, separate audit from debug logs, set retention and verify delivery during rotation/restart."],"configuration_example":null,"required_fields":["process_id","api","path","result"],"example":{"schema":"1200km.telemetry.example.v1","synthetic":true,"timestamp":"2026-09-27T12:00:00Z","telemetry_id":"DC0021","collector":"illustrative-lab-collector","observation":{"process_id":4200,"api":"CreateFileW","path":"C:\\Lab\\demo.txt","result":"success"}},"example_note":"Project-normalized synthetic JSON, not a native provider log, captured event, attack verdict or validated detection. A parser/adapter is required for a real SIEM. Example names, IPs and values are fictional.","limitations":"Debug output is not necessarily a durable audit trail. Application developers must emit the relevant event; installing a log pipeline does not make an absent event exist.","sources":[{"id":"otel","title":"OpenTelemetry log data model","url":"https://opentelemetry.io/docs/specs/otel/logs/data-model/"}],"association":"attack_component","anomaly_design":"Per application, client and route: request rate, rare actions, failure ratios and unusual state transitions. Version changes, retries, health probes and seasonal load need separate baselines."}],"detection":{"key":"mobile/T1521","id":"T1521","name":"Encrypted Channel","domain":"mobile","platforms":["Android","iOS"],"environments":["mobile"],"source_url":"https://attack.mitre.org/techniques/T1521","technique_page":"techniques/mobile/T1521/","page":"detections/mobile/T1521/","status":"guidance_only","counts":{"sigma":0,"atlas_basic":0,"atlas_anomaly":0,"strategies":1,"analytics":2,"live_validated":0},"sigma_rules":[],"atlas_basic":[],"atlas_anomaly":[],"anomaly_types":[],"strategies":[{"id":"DET0641","name":"Detection of Encrypted Channel","url":"https://attack.mitre.org/detectionstrategies/DET0641","stix_id":"x-mitre-detection-strategy--6e373a06-358b-4078-a8ab-1f5c1730ddf4","relationship_id":"relationship--c15acd70-6527-4788-baa9-51a11b996164","description":"","analytics":[{"id":"AN1716","name":"Analytic 1716","guidance":"For Android, detect Encrypted Channel from documented management, network, or vetting evidence; treat state queries as periodic observations rather than real-time events. Correlate Application Permission via Android Enterprise DPC / Application Vetting [DevicePolicyManager.getPermissionGrantState(); PackageManager manifest/requested-permission review]; Application State via Android Enterprise / EMM [Managed package inventory/status and package metadata]; File Creation via Application Vetting / Forensic Acquisition [Dynamic filesystem trace or acquired app-container/filesystem artifacts: App writes high-entropy blob (Shannon entropy > $EntropyThreshold$) to local staging path immediately before outbound transmission — encrypted staging artifact confirms app-layer encryption occurred]. Alert on a sequence or state change inconsistent with the device/app baseline, approved management policy, or expected user workflow; do not infer unobserved API calls, file/process activity, or payload content from management state alone.","url":"https://attack.mitre.org/detectionstrategies/DET0641#AN1716","platforms":["Android"],"tuning":[{"field":"ApprovedCryptoApps","description":"VPN clients, enterprise secure messaging (Signal, approved messaging), MDM agent, encryption-declared apps. Derive from MDM catalog."},{"field":"EntropyThreshold","description":"Default 7.0 bits Shannon entropy for staged file. Calibrate from legitimate app file baseline. Files above threshold are likely encrypted or compressed."},{"field":"AppCDNList","description":"30-day per-app network destination baseline."},{"field":"InteractionThreshold","description":"Default 300s."}],"log_sources":[{"component_id":"DC0114","component":"Application Permission","name":"android:DevicePolicyManager","channel":"DevicePolicyManager.getPermissionGrantState(); PackageManager manifest/requested-permission review","platforms":["Android"],"analytic_id":"AN1716","source_url":"https://attack.mitre.org/detectionstrategies/DET0641#AN1716","validation":"upstream_definition_not_locally_validated","component_page":"telemetry/DC0114/"},{"component_id":"DC0123","component":"Application State","name":"android:EMM","channel":"Managed package inventory/status and package metadata","platforms":["Android"],"analytic_id":"AN1716","source_url":"https://attack.mitre.org/detectionstrategies/DET0641#AN1716","validation":"upstream_definition_not_locally_validated","component_page":"telemetry/DC0123/"},{"component_id":"DC0039","component":"File Creation","name":"mobile:ForensicArtifacts","channel":"Dynamic filesystem trace or acquired app-container/filesystem artifacts: App writes high-entropy blob (Shannon entropy > $EntropyThreshold$) to local staging path immediately before outbound transmission — encrypted staging artifact confirms app-layer encryption occurred","platforms":["Android"],"analytic_id":"AN1716","source_url":"https://attack.mitre.org/detectionstrategies/DET0641#AN1716","validation":"upstream_definition_not_locally_validated","component_page":"telemetry/DC0039/"},{"component_id":"DC0021","component":"OS API Execution","name":"mobile:DynamicAnalysis","channel":"Dynamic API/runtime trace: App invokes cryptographic functions (javax.crypto.Cipher, Android KeyStore, AES/RSA/ECC operations) on data buffer followed by encode-then-transmit sequence NOT matching app declared network function — app-layer crypto on data before transm","platforms":["Android"],"analytic_id":"AN1716","source_url":"https://attack.mitre.org/detectionstrategies/DET0641#AN1716","validation":"upstream_definition_not_locally_validated","component_page":"telemetry/DC0021/"}]},{"id":"AN1717","name":"Analytic 1717","guidance":"Indirect evidence of application-layer encrypted channel usage inferred through anomalous background processing and network transmission patterns following application activity, where encryption operations are not directly observable. Detection correlates background execution + network behavior + application entitlement posture to identify misuse of encrypted communication channels.","url":"https://attack.mitre.org/detectionstrategies/DET0641#AN1717","platforms":["iOS"],"tuning":[{"field":"TimeWindow","description":"Correlation window between background processing and network transmission"},{"field":"AllowedAppList","description":"Apps expected to use encrypted communication channels"},{"field":"EntropyThreshold","description":"Threshold for identifying encoded/encrypted payloads"},{"field":"BeaconIntervalVariance","description":"Tolerance for periodic communication patterns"}],"log_sources":[]}]}],"telemetry_references":[{"id":"DC0114","name":"Application Permission","tag":"Application Permission","page":"telemetry/DC0114/","kind":"attack_component"},{"id":"DC0123","name":"Application State","tag":"Application State","page":"telemetry/DC0123/","kind":"attack_component"},{"id":"DC0039","name":"File Creation","tag":"File Creation","page":"telemetry/DC0039/","kind":"attack_component"},{"id":"DC0021","name":"OS API Execution","tag":"OS API Execution","page":"telemetry/DC0021/","kind":"attack_component"}],"visibility":"source_mapped","visibility_note":null,"tool_references":[],"related_parent":null,"article_url":"https://1200km.com/articles/read/2026/2026-04-20-malicious-activity-as-a-statistical-signal-a-detection-engineering-analysis-of-anomaly-bas-90df8b6dea12/","validation":{"source_join":"exact_ids","sigma_yaml":"parsed","backend_compilation":"not_run","live_telemetry":"not_run","detection_execution":"not_run"}},"tools":[],"software":[{"id":"S0302","name":"Twitoor","url":"https://attack.mitre.org/software/S0302","kind":"malware","description":"[Twitoor](https://attack.mitre.org/software/S0302) encrypts its C2 communication.(Citation: ESET-Twitoor)","relationship_id":"relationship--c6464a84-e23b-412f-b435-5b23853d3643","references":[{"source_name":"ESET-Twitoor","description":"ESET. (2016, August 24). First Twitter-controlled Android botnet discovered. Retrieved December 22, 2016.","url":"http://www.welivesecurity.com/2016/08/24/first-twitter-controlled-android-botnet-discovered/"}]},{"id":"S1095","name":"AhRat","url":"https://attack.mitre.org/software/S1095","kind":"malware","description":"[AhRat](https://attack.mitre.org/software/S1095) can communicate with the C2 using HTTPS requests.(Citation: welivesecurity_ahrat_0523)","relationship_id":"relationship--9fb0c414-6216-4b42-a080-cb42ef4011c5","references":[{"source_name":"welivesecurity_ahrat_0523","description":"Lukas Stefanko. (2023, May 23). Android app breaking bad: From legitimate screen recording to file exfiltration within a year. Retrieved December 18, 2023.","url":"https://www.welivesecurity.com/2023/05/23/android-app-breaking-bad-legitimate-screen-recording-file-exfiltration/"}]}],"actors":[],"mitigations":[],"candidates":[],"simulation":{"atomic_status":"no_atomic_candidate","lab_execution":"not_run","browser_attack_runner":false,"prerequisites":"Use owned test devices or emulators, disposable app accounts and test data. Verify platform/version instrumentation; desktop test procedures do not establish mobile coverage.","scenario":null},"validation":{"source_identity":"checked_against_pinned_source","relationship_join":"exact_ids_no_inheritance","page_contract":"automated_checks_required","sensor_capture":"not_run","detection_backend":"not_run","adversary_simulation":"not_run","independent_incident_fact_check":"not_performed"},"technique_links":{"T1521":"/ttp-simulation/techniques/mobile/T1521/"},"synthetic":{"schema":"1200km.ttp.collection-fixture.v1","synthetic":true,"technique_key":"mobile/T1521","purpose":"Collection/parser contract exercise, NOT a positive example or detection of this TTP.","events":[{"schema":"1200km.telemetry.example.v1","synthetic":true,"timestamp":"2026-09-27T12:00:00Z","telemetry_id":"DC0114","collector":"illustrative-lab-collector","observation":{"package":"test.example.lab","permission":"android.permission.CAMERA","declared":true,"granted":false}},{"schema":"1200km.telemetry.example.v1","synthetic":true,"timestamp":"2026-09-27T12:00:00Z","telemetry_id":"DC0123","collector":"illustrative-lab-collector","observation":{"package":"test.example.lab","state_before":"background","state_after":"foreground","source":"own_app_callback"}},{"schema":"1200km.telemetry.example.v1","synthetic":true,"timestamp":"2026-09-27T12:00:00Z","telemetry_id":"DC0039","collector":"illustrative-lab-collector","observation":{"process_id":4200,"path":"C:\\Lab\\demo.txt","action":"create","size_bytes":64}},{"schema":"1200km.telemetry.example.v1","synthetic":true,"timestamp":"2026-09-27T12:00:00Z","telemetry_id":"DC0021","collector":"illustrative-lab-collector","observation":{"process_id":4200,"api":"CreateFileW","path":"C:\\Lab\\demo.txt","result":"success"}}]}}