| ID | Name |
|---|---|
| T1481.001 | Dead Drop Resolver |
| T1481.002 | Bidirectional Communication |
| T1481.003 | One-Way Communication |
Adversaries may use an existing, legitimate external Web service channel as a means for sending commands to a compromised system without receiving return output. Compromised systems may leverage popular websites and social media to host command and control (C2) instructions. Those infected systems may opt to send the output from those commands back over a different C2 channel, including to another distinct Web service. Alternatively, compromised systems may return no output at all in cases where adversaries want to send instructions to systems and do not want a response.
Popular websites and social media, acting as a mechanism for C2, may give a significant amount of cover. This is due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google or Twitter, makes it easier for adversaries to hide in expected noise. Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.
This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0610 | Detection of One-Way Communication | AN1663 |
The defender correlates repeated or periodic app-attributed retrieval from a legitimate public web-service platform with runtime conditions showing that the retrieval is not aligned to normal foreground consumption, user interaction, or approved app role. The strongest Android evidence is a managed or installed app repeatedly issuing inbound-oriented GET, fetch, sync, or content-pull operations to social, collaboration, paste, code-hosting, cloud-storage, messaging, or generic HTTPS platforms while the app is backgrounded, while the device is locked, or without recent user interaction, and without a corresponding outbound writeback to that same service class during the operational window. The detection is strengthened when the retrieval is temporally adjacent to scheduled/background execution, local state changes, or later downstream effects that do not require the same public platform to receive output. |
| AN1664 |
The defender correlates repeated retrieval-oriented communication from a supervised device or managed iOS app to a legitimate public web-service platform where the activity remains primarily inbound and does not produce corresponding writeback to that same service class during the operational window. The strongest iOS evidence is managed-app or device-attributed communication to collaboration, social, messaging, storage, or generic HTTPS platforms where inbound fetches or content pulls recur during background refresh, while the device is locked, or without recent user interaction, and no matching POST, upload, update, or message-send activity to that same public service class is observed. Because direct local runtime visibility is weaker than Android, the primary analytic is anchored on network directionality plus supervised managed-app and device-state context. |