T1027 Obfuscated Files or Information

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®

CRI Profile Mappings

Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
DE.AE-02.01 Event analysis and detection Mitigates T1027 Obfuscated Files or Information
Comments
This diagnostic statement provides for implementation of methods to block similar future attacks via security tools such as antivirus and IDS/IPS to provide protection against threats and exploitation attempts.
References
    PR.IR-01.08 End-user device access Mitigates T1027 Obfuscated Files or Information
    Comments
    This diagnostic statement implements technical controls (e.g., VPN, antivirus software) to address the risks of end-user personal computing devices accessing the organization’s network and resources.
    References
      PR.PS-05.01 Malware prevention Mitigates T1027 Obfuscated Files or Information
      Comments
      Antivirus/Antimalware software can be utilized to detect and quarantine suspicious files that adversaries have made difficult to discover by encrypting, encoding, or obfuscating.
      References
        PR.PS-01.01 Configuration baselines Mitigates T1027 Obfuscated Files or Information
        Comments
        This diagnostic statement provides for securely configuring production systems. This includes hardening default configurations and making security-focused setting adjustments to reduce the attack surface, enforce best practices, and protect sensitive data thereby mitigating adversary exploitation.
        References
          PR.PS-01.08 End-user device protection Mitigates T1027 Obfuscated Files or Information
          Comments
          This diagnostic statement protects against Obfuscated Files or Information through the use of limiting access to resources to only authorized devices, management of personal computing devices, network intrusion prevention, and the use of antimalware.
          References

            NIST 800-53 Mappings

            Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
            CM-06 Configuration Settings mitigates T1027 Obfuscated Files or Information
            SI-02 Flaw Remediation mitigates T1027 Obfuscated Files or Information
            SI-03 Malicious Code Protection mitigates T1027 Obfuscated Files or Information
            SI-07 Software, Firmware, and Information Integrity mitigates T1027 Obfuscated Files or Information
            CM-02 Baseline Configuration mitigates T1027 Obfuscated Files or Information
            CM-07 Least Functionality mitigates T1027 Obfuscated Files or Information
            SI-04 System Monitoring mitigates T1027 Obfuscated Files or Information
            AC-03 Access Enforcement mitigates T1027 Obfuscated Files or Information

            VERIS Mappings

            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

            Azure Mappings

            Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
            microsoft_sentinel Microsoft Sentinel technique_scores T1027 Obfuscated Files or Information
            Comments
            The Microsoft Sentinel Analytics "Powershell Empire cmdlets seen in command line" query can detect the use of Empire, which can obfuscate commands using Invoke-Obfuscation, but does not address other procedures.
            References
            alerts_for_linux_machines Alerts for Linux Machines technique_scores T1027 Obfuscated Files or Information
            Comments
            This control only provides detection coverage for the Compile After Delivery sub-technique while not providing detection for all other sub-techniques relevant to the Linux platform or most of its procedure examples. As a result of this minimal coverage, the overall score is assessed as Minimal.
            References
            alerts_for_windows_machines Alerts for Windows Machines technique_scores T1027 Obfuscated Files or Information
            Comments
            This control may detect usage of VBScript.Encode and base-64 encoding to obfuscate malicious commands and scripts. The following alerts may be generated: "Detected suspicious execution of VBScript.Encode command", "Detected encoded executable in command line data".
            References
            defender_for_app_service Microsoft Defender for Cloud: Defender for App Service technique_scores T1027 Obfuscated Files or Information
            microsoft_antimalware_for_azure Microsoft Antimalware for Azure technique_scores T1027 Obfuscated Files or Information
            microsoft_antimalware_for_azure Microsoft Antimalware for Azure technique_scores T1027 Obfuscated Files or Information

            GCP Mappings

            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

            M365 Mappings

            Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
            EOP-AMW-E3 Antimalware Technique Scores T1027 Obfuscated Files or Information
            Comments
            In Microsoft 365 organizations with mailboxes in Exchange Online or standalone Exchange Online Protection (EOP) organizations without Exchange Online mailboxes, email messages are automatically protected against malware by EOP. Some of the major categories of malware are: Viruses that infect other programs and data, and spread through your computer or network looking for programs to infect. Spyware that gathers your personal information, such as sign-in information and personal data, and sends it back to its author. Ransomware that encrypts your data and demands payment to decrypt it. Anti-malware software doesn't help you decrypt encrypted files, but it can detect the malware payload that's associated with the ransomware. EOP offers multi-layered malware protection that's designed to catch all known malware in Windows, Linux, and Mac that travels into or out of your organization. The following options help provide anti-malware protection: Layered defenses against malware: Multiple anti-malware scan engines help protect against both known and unknown threats. These engines include powerful heuristic detection to provide protection even during the early stages of a malware outbreak. This multi-engine approach has been shown to provide significantly more protection than using just one anti-malware engine. Real-time threat response: During some outbreaks, the anti-malware team might have enough information about a virus or other form of malware to write sophisticated policy rules that detect the threat, even before a definition is available from any of the scan engines used by the service. These rules are published to the global network every 2 hours to provide your organization with an extra layer of protection against attacks. Fast anti-malware definition deployment: The anti-malware team maintains close relationships with partners who develop anti-malware engines. As a result, the service can receive and integrate malware definitions and patches before they're publicly released. Our connection with these partners often allows us to develop our own remedies as well. The service checks for updated definitions for all anti-malware engines every hour. License Requirements: M365 E3 or Microsoft Defender for Office plan 1.
            References
            DEF-QUAR-E3 Quarantine Policies Technique Scores T1027 Obfuscated Files or Information
            Comments
            In Exchange Online Protection (EOP) and Microsoft Defender for Office 365, quarantine policies allow admins to define the user experience for quarantined messages. Traditionally, users have been allowed or denied levels of interactivity with quarantine messages based on why the message was quarantined. For example, users can view and release messages that were quarantined as spam or bulk, but they can't view or release messages that were quarantined as high confidence phishing or malware. The following M365 features are supported by quarantine policies, “Response” to Anti-malware and Anti-Phishing tagged items. Files that are quarantined as malware by Safe Attachments for SharePoint, OneDrive, and Microsoft Teams. License requirements: M365 E3 (or Defender for Office plan 1)
            References
            DEF-ZHAP-E3 Zero Hour Auto Purge Technique Scores T1027 Obfuscated Files or Information
            Comments
            Zero-hour auto purge (ZAP) is a protection feature in Exchange Online Protection (EOP) that retroactively detects and neutralizes malicious phishing, spam, or malware messages that have already been delivered to Exchange Online mailboxes. With the E5 licensing or Office Plan 2, ZAP is also able to retroactively detect existing malicious chat messages in Microsoft Teams that are identified as malware or high confidence phishing. License Requirements: ZAP for Defender O365 is included with M365's E3 and requires E5 when leveraging ZAP for Teams security.
            References

            ATT&CK Subtechniques

            Technique ID Technique Name Number of Mappings
            T1027.011 Fileless Storage 6
            T1027.009 Embedded Payloads 15
            T1027.013 Encrypted/Encoded File 14
            T1027.008 Stripped Payloads 7
            T1027.001 Binary Padding 1
            T1027.012 LNK Icon Smuggling 11
            T1027.005 Indicator Removal from Tools 7
            T1027.014 Polymorphic Code 14
            T1027.003 Steganography 1
            T1027.004 Compile After Delivery 3
            T1027.006 HTML Smuggling 4
            T1027.010 Command Obfuscation 17
            T1027.002 Software Packing 12
            T1027.007 Dynamic API Resolution 9