Command Line
certutil -encode [Input] [Output]
Description
CertUtil is often abused by cyber threats to encode Base64 data or files.
Risk
High
Risk Reason
Usage of certutil to encode Base64 data or files should be highly scrutinized due to it's prevalence in cyber-threat activities.
Fidelity
High
Fidelity Reason
This type of commandline activity is typically uncommon for users, or very predictable.
Operating Systems
Killchain Phases
References
MITRE ATT&CK TECHNIQUES
URL: https://attack.mitre.org/techniques/T1140
Description: Adversaries may use [Obfuscated Files or Information](https://attack.mitre.org/techniques/T1027) 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 use of [certutil](https://attack.mitre.org/software/S0160) 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 copy /b command to reassemble binary fragments into a malicious payload. (Citation: Carbon Black Obfuscation Sept 2016)
Sometimes a user's action may be required to open it for deobfuscation or decryption as part of [User Execution](https://attack.mitre.org/techniques/T1204). 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)
Tactics: