Sub-technique of T1480 Execution Guardrails.View on attack.mitre.org
Adversaries may environmentally key payloads or other features of malware to evade defenses and constraint execution to a specific target environment. Environmental keying uses cryptography to constrain execution or actions based on adversary supplied environment specific conditions that are expected to be present on the target. Environmental keying is an implementation of Execution Guardrails that utilizes cryptographic techniques for deriving encryption/decryption keys from specific types of values in a given computing environment.
Values can be derived from target-specific elements and used to generate a decryption key for an encrypted payload. Target-specific values can be derived from specific network shares, physical devices, software/software versions, files, joined AD domains, system time, and local/external IP addresses. By generating the decryption keys from target-specific environmental values, environmental keying can make sandbox detection, anti-virus detection, crowdsourcing of information, and reverse engineering difficult. These difficulties can slow down the incident response process and help adversaries hide their tactics, techniques, and procedures (TTPs).
Similar to Obfuscated Files or Information, adversaries may use environmental keying to help protect their TTPs and evade detection. Environmental keying may be used to deliver an encrypted payload to the target that will use target-specific values to decrypt the payload before execution. By utilizing target-specific values to decrypt the payload the adversary can avoid packaging the decryption key with the payload or sending it over a potentially monitored network connection. Depending on the technique for gathering target-specific values, reverse engineering of the encrypted payload can be exceptionally difficult. This can be used to prevent exposure of capabilities in environments that are not intended to be compromised or operated within.
Like other Execution Guardrails, environmental keying can be used to prevent exposure of capabilities in environments that are not intended to be compromised or operated within. This activity is distinct from typical Virtualization/Sandbox Evasion. While use of Virtualization/Sandbox Evasion may involve checking for known sandbox values and continuing with execution only if there is no match, the use of environmental keying will involve checking for an expected target-specific value that must match for decryption and subsequent execution to be successful.
Rules on DetectionCode tagged with T1480.001.
None recorded.
| Used by | Procedure example |
|---|---|
| GroupAPT41 | APT41 has encrypted payloads using the Data Protection API (DPAPI), which relies on keys tied to specific user accounts on specific machines. APT41 has also environmentally keyed second stage malware with an RC5 key derived in part from the infected system's volume serial number. |
| GroupEquation | Equation has been observed utilizing environmental keying in payload delivery. |
| Used by | Procedure example |
|---|---|
| MalwareInvisiMole | InvisiMole can use Data Protection API to encrypt its components on the victim’s computer, to evade detection, and to make sure the payload can only be decrypted and loaded on one specific compromised computer. |
| MalwareNinja | Ninja can store its final payload in the Registry under `$HKLM\SOFTWARE\Classes\Interface\` encrypted with a dynamically generated key based on the drive’s serial number. |
| MalwarePikabot | Pikabot stops execution if the infected system language matches one of several languages, with various versions referencing: Georgian, Kazakh, Uzbek, Tajik, Russian, Ukrainian, Belarussian, and Slovenian. |
| MalwarePowerPunch | PowerPunch can use the volume serial number from a target host to generate a unique XOR key for the next stage payload. |
| MalwarePUBLOAD | PUBLOAD has utilized environmental keying in the payload to include the victim volume serial number, computer name, username, and machine’s tick count. |
| MalwareROKRAT | ROKRAT relies on a specific victim hostname to execute and decrypt important strings. |
| MalwareTONESHELL | TONESHELL has generated unique GUIDs to identify victim devices. TONESHELL has leveraged environmental keying in payload delivery using the victim computer name and other configuration values. TONESHELL has also tracked IDs associated with reverse shell subprocesses to manage interactions and terminations from C2. |
| MalwareWinnti for Windows | The Winnti for Windows dropper component can verify the existence of a single command line parameter and either terminate if it is not found or later use it as a decryption key. |
Data from MITRE ATT&CK® (Enterprise). ATT&CK® is a registered trademark of The MITRE Corporation.
