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Deobfuscate/Decode Files or Information (T1140) is a MITRE ATT&CK technique associated with Stealth . Adversaries may use Obfuscated Files or Information to hide artifacts of an intrusion from analysis.
Deobfuscate/Decode Files or Information (T1140) is a MITRE ATT&CK technique associated with Stealth. Adversaries may use Obfuscated Files or Information to hide artifacts of an intrusion from analysis.
Attackers use Deobfuscate/Decode Files or Information because it provides a reliable way to advance their objective within the Stealth tactic, often with a favorable balance of impact versus detectability on ESXi, Linux, macOS, Windows environments. Defenders should assess this behavior in the context of the affected platform and adjacent activity rather than treating it as a standalone indicator.
Adversaries may use Obfuscated Files or Information to hide artifacts of an intrusion from analysis. They may require separate mechanisms to decode or deobfuscate that information depending on how they intend to use it. Methods for doing that include built-in functionality of malware or by using utilities present on the system.
One such example is the use of certutil to decode a remote access tool portable executable file that has been hidden inside a certificate file.(Citation: Malwarebytes Targeted Attack against Saudi Arabia) Another example is using the Windows <code>copy /b</code> or <code>type</code> command to reassemble binary fragments into a malicious payload.(Citation: Carbon Black Obfuscation Sept 2016)(Citation: Sentinel One Tainted Love 2023)
Sometimes a user's action may be required to open it for deobfuscation or decryption as part of User Execution. The user may also be required to input a password to open a password protected compressed/encrypted file that was provided by the adversary.(Citation: Volexity PowerDuke November 2016)
No universal command represents Deobfuscate/Decode Files or Information. Capture the exact command line, arguments, parent process, account, host, and execution time from the investigated environment; do not operationalize unverified examples.
| Event ID | Log Channel | What It Indicates |
|---|---|---|
| Environment-specific | Relevant Windows channel(s) | Correlate authentication, process, object-access, and configuration events with the observed execution context. |
| Sysmon Event ID | Name | Why It's Relevant Here |
|---|---|---|
| Environment-specific | Validate configured telemetry | Use process, network, file, registry, DNS, or image-load telemetry only when relevant and enabled. |
No MITRE detection guidance published for this technique.
Relevant ATT&CK Data Sources: N/A
A universal Sigma rule would create unreliable results because this technique has no single guaranteed observable. Build detection logic from a documented behavior and supported data source, scope it to the affected platform, and validate it against benign administrative activity before deployment.
Start with the data sources named in the detection section. Scope searches by asset, identity, and time window; correlate the primary behavior with preceding access and subsequent actions. A portable query is intentionally not provided where the technique lacks a universal schema or observable.
No MITRE mitigations mapped to this technique.