Defense evasion consists of techniques an adversary may use to evade detection or avoid other defenses. Sometimes these actions are the same as or variations of techniques in other categories that have the added benefit of subverting a particular defense or mitigation. Defense evasion may be considered a set of attributes the adversary applies to all other phases of the operation.
|T1453||Abuse Accessibility Features|
Adversaries may seek to identify all applications installed on the device. One use case for doing so is to identify the presence of endpoint security applications that may increase the adversary's risk of detection. Another use case is to identify the presence of applications that the adversary may wish to target.
An adversary may seek to lock the legitimate user out of the device, for example to inhibit user interaction or to obtain a ransom payment.
|T1408||Disguise Root/Jailbreak Indicators||
An adversary could use knowledge of the techniques used by security software to evade detection. For example, some mobile security products perform compromised device detection by searching for particular artifacts such as an installed "su" binary, but that check could be evaded by naming the binary something else. Similarly, polymorphic code techniques could be used to evade signature-based detection.
|T1407||Download New Code at Runtime||
An app could download and execute dynamic code (not included in the original application package) after installation to evade static analysis techniques (and potentially dynamic analysis techniques) used for application vetting or application store review.
|T1523||Evade Analysis Environment||
Malicious applications may attempt to detect their operating environment prior to fully executing their payloads. These checks are often used to ensure the application is not running within an analysis environment such as a sandbox used for application vetting, security research, or reverse engineering.
A malicious application can inject input to the user interface to mimic user interaction through the abuse of Android's accessibility APIs.
|T1478||Install Insecure or Malicious Configuration||
An adversary could attempt to install insecure or malicious configuration settings on the mobile device, through means such as phishing emails or text messages either directly containing the configuration settings as an attachment, or containing a web link to the configuration settings. The device user may be tricked into installing the configuration settings through social engineering techniques .
|T1398||Modify OS Kernel or Boot Partition||
If an adversary can escalate privileges, he or she may be able to use those privileges to place malicious code in the device kernel or other boot partition components, where the code may evade detection, may persist after device resets, and may not be removable by the device user. In some cases (e.g., the Samsung Knox warranty bit as described under Detection), the attack may be detected but could result in the device being placed in a state that no longer allows certain functionality.
|T1400||Modify System Partition||
If an adversary can escalate privileges, he or she may be able to use those privileges to place malicious code in the device system partition, where it may persist after device resets and may not be easily removed by the device user.
|T1399||Modify Trusted Execution Environment||
If an adversary can escalate privileges, he or she may be able to use those privileges to place malicious code in the device's Trusted Execution Environment (TEE) or other similar isolated execution environment where the code can evade detection, may persist after device resets, and may not be removable by the device user. Running code within the TEE may provide an adversary with the ability to monitor or tamper with overall device behavior.
|T1406||Obfuscated Files or Information||
An app could contain malicious code in obfuscated or encrypted form, then deobfuscate or decrypt the code at runtime to evade many app vetting techniques.
|T1508||Suppress Application Icon||
A malicious application could suppress its icon from being displayed to the user in the application launcher to hide the fact that it is installed, and to make it more difficult for the user to uninstall the application. Hiding the application's icon programmatically does not require any special permissions.