Adversaries may attempt to make an executable or file difficult to discover or analyze by encrypting, encoding, or otherwise obfuscating its contents on the system or in transit. This is common behavior that can be used across different platforms and the network to evade defenses. 

Payloads may be compressed, archived, or encrypted in order to avoid detection. These payloads may be used during Initial Access or later to mitigate detection. Sometimes a user's action may be required to open and [Deobfuscate/Decode Files or Information](https://attack.mitre.org/techniques/T1140) for [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) Adversaries may also use compressed or archived scripts, such as JavaScript. 

Portions of files can also be encoded to hide the plain-text strings that would otherwise help defenders with discovery. (Citation: Linux/Cdorked.A We Live Security Analysis) Payloads may also be split into separate, seemingly benign files that only reveal malicious functionality when reassembled. (Citation: Carbon Black Obfuscation Sept 2016)

Adversaries may also abuse [Command Obfuscation](https://attack.mitre.org/techniques/T1027/010) to obscure commands executed from payloads or directly via [Command and Scripting Interpreter](https://attack.mitre.org/techniques/T1059). Environment variables, aliases, characters, and other platform/language specific semantics can be used to evade signature based detections and application control mechanisms. (Citation: FireEye Obfuscation June 2017) (Citation: FireEye Revoke-Obfuscation July 2017)(Citation: PaloAlto EncodedCommand March 2017) 
Obfuscated Files or Information
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1027  external_id: T1027     source_name: Volexity PowerDuke November 2016  description: Adair, S.. (2016, November 9). PowerDuke: Widespread Post-Election Spear Phishing Campaigns Targeting Think Tanks and NGOs. Retrieved January 11, 2017.  url: https://www.volexity.com/blog/2016/11/09/powerduke-post-election-spear-phishing-campaigns-targeting-think-tanks-and-ngos/     source_name: GitHub Revoke-Obfuscation  description: Bohannon, D. (2017, July 27). Revoke-Obfuscation. Retrieved February 12, 2018.  url: https://github.com/danielbohannon/Revoke-Obfuscation     source_name: FireEye Obfuscation June 2017  description: Bohannon, D. & Carr N. (2017, June 30). Obfuscation in the Wild: Targeted Attackers Lead the Way in Evasion Techniques. Retrieved February 12, 2018.  url: https://web.archive.org/web/20170923102302/https://www.fireeye.com/blog/threat-research/2017/06/obfuscation-in-the-wild.html     source_name: FireEye Revoke-Obfuscation July 2017  description: Bohannon, D. & Holmes, L. (2017, July 27). Revoke-Obfuscation: PowerShell Obfuscation Detection Using Science. Retrieved February 12, 2018.  url: https://www.fireeye.com/content/dam/fireeye-www/blog/pdfs/revoke-obfuscation-report.pdf     source_name: GitHub Office-Crackros Aug 2016  description: Carr, N. (2016, August 14). OfficeCrackros. Retrieved February 12, 2018.  url: https://github.com/itsreallynick/office-crackros     source_name: Linux/Cdorked.A We Live Security Analysis  description: Pierre-Marc Bureau. (2013, April 26). Linux/Cdorked.A: New Apache backdoor being used in the wild to serve Blackhole. Retrieved September 10, 2017.  url: https://www.welivesecurity.com/2013/04/26/linuxcdorked-new-apache-backdoor-in-the-wild-serves-blackhole/     source_name: Carbon Black Obfuscation Sept 2016  description: Tedesco, B. (2016, September 23). Security Alert Summary. Retrieved February 12, 2018.  url: https://www.carbonblack.com/2016/09/23/security-advisory-variants-well-known-adware-families-discovered-include-sophisticated-obfuscation-techniques-previously-associated-nation-state-attacks/     source_name: PaloAlto EncodedCommand March 2017  description: White, J. (2017, March 10). Pulling Back the Curtains on EncodedCommand PowerShell Attacks. Retrieved February 12, 2018.  url: https://researchcenter.paloaltonetworks.com/2017/03/unit42-pulling-back-the-curtains-on-encodedcommand-powershell-attacks/     