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 for 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) 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 to obscure commands executed from payloads or directly via Command and Scripting Interpreter. 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)
View in MITRE ATT&CK®| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| CIS-10.1 | Deploy and Maintain Anti-Malware Software | mitigates | T1027 | Obfuscated Files or Information |
Comments
Anti-malware software can detect and quarantine malicious files or commands that use encoding, packing, encryption, or other obfuscation techniques to evade detection.
References
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| CIS-10.7 | Use Behavior-Based Anti-Malware Software | mitigates | T1027 | Obfuscated Files or Information |
Comments
Behavior-based anti-malware can identify malicious activity after obfuscated content is decoded, unpacked, interpreted, or executed, allowing detection or blocking based on runtime behavior rather than relying solely on static signatures.
References
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| CIS-13.7 | Deploy a Host-Based Intrusion Prevention Solution | mitigates | T1027 | Obfuscated Files or Information |
Comments
Host-based intrusion prevention capabilities can enforce behavioral rules that prevent execution of potentially obfuscated scripts or payloads.
References
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| CIS-9.7 | Deploy and Maintain Email Server Anti-Malware Protections | mitigates | T1027 | Obfuscated Files or Information |
Comments
Email anti-malware can use static, heuristic, and behavioral analysis to identify obfuscated files before delivery.
References
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| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| action.hacking.variety.Evade Defenses | Modification of the action (rather than the system, as in 'Disable controls') to avoid detection. | related-to | T1027 | Obfuscated Files or Information | |
| action.hacking.variety.Null byte injection | Null byte injection. Child of 'Exploit vuln'. | related-to | T1027 | Obfuscated Files or Information | |
| action.malware.variety.Disable controls | Disable or interfere with security controls | related-to | T1027 | Obfuscated Files or Information |
| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| google_secops | Google Security Operations | technique_scores | T1027 | Obfuscated Files or Information |
Comments
Google Security Ops is able to trigger an alert based off suspicious command line arguments or processes that indicate obfuscation techniques to evade cyber defenses. For example, when cmd.exe has been obfuscated. This mapping was scored as minimal based on low or uncertain detection coverage factor of the technique.
https://github.com/chronicle/detection-rules/blob/783e0e5947774785db1c55041b70176deeca6f46/soc_prime_rules/threat_hunting/windows/detect_cmd_exe_obfuscation.yaral
https://github.com/chronicle/detection-rules/blob/783e0e5947774785db1c55041b70176deeca6f46/soc_prime_rules/threat_hunting/windows/ursnif_trojan_detection__cmd_obfuscation.yaral
References
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| Technique ID | Technique Name | Number of Mappings |
|---|---|---|
| T1027.011 | Fileless Storage | 3 |
| T1027.009 | Embedded Payloads | 4 |
| T1027.013 | Encrypted/Encoded File | 5 |
| T1027.001 | Binary Padding | 1 |
| T1027.016 | Junk Code Insertion | 1 |
| T1027.017 | SVG Smuggling | 2 |
| T1027.012 | LNK Icon Smuggling | 6 |
| T1027.005 | Indicator Removal from Tools | 6 |
| T1027.014 | Polymorphic Code | 3 |
| T1027.003 | Steganography | 1 |
| T1027.004 | Compile After Delivery | 2 |
| T1027.006 | HTML Smuggling | 2 |
| T1027.010 | Command Obfuscation | 5 |
| T1027.002 | Software Packing | 4 |
| T1027.018 | Invisible Unicode | 1 |
| T1027.007 | Dynamic API Resolution | 3 |
| T1027.015 | Compression | 3 |