Query: what is T1027.015
Matching passage: T1027.015 Compression. Tactics: stealth. Description: Adversaries may use compression to obfuscate their payloads or files. Compressed file formats such as ZIP, gzip, 7z, and RAR can compress and archive multiple files together to make it easier and faster to transfer files. In addition to compressing files, adversaries may also compress shellcode directly - for example, in order to store it in a Windows Registry key (i.e., [Fileless Storage](https://attack.mitre.org/techniques/T1027/011)).(Citation: Trustwave Pillowmint June 2020) In order to further evade detection, adversaries may combine multiple ZIP files into one archive. This process of concatenation creates an archive that appears to be a single archive but in fact contains the central directories of the embedded archives. Some ZIP readers, such as 7zip, may not be able to identify concatenated ZIP files and miss the presence of the malicious payload.(Citation: Perception Point) File archives may be sent as one [Spearphishing Attachment](https://attack.mitre.org/techniques/T1566/001) through email. Adversaries have sent malicious payloads as archived files to encourage the user to interact with and extract the malicious payload onto their system (i.e., [Malicious File](https://attack.mitre.org/techniques/T1204/002)).(Citation: NTT Security Flagpro new December 2021) However, some file compression tools, such as 7zip, can be used to produce self-extracting archives. Adversaries may send self-extracting archives to hide the functionality of their payload and launch it without requiring multiple actions from the user.(Citation: The Hacker News) [Compression](https://attack.mitre.org/techniques/T1027/015) may be used in combination with [Encrypted/Encoded File](https://attack.mitre.org/techniques/T1027/013) where compressed files are encrypted and password-protected.
Near-miss passage: T1027.010 Command Obfuscation. Tactics: stealth. Description: Adversaries may obfuscate content during command execution to impede detection. Command-line obfuscation is a method of making strings and patterns within commands and scripts more difficult to signature and analyze. This type of obfuscation can be included within commands executed by delivered payloads (e.g., [Phishing](https://attack.mitre.org/techniques/T1566) and [Drive-by Compromise](https://attack.mitre.org/techniques/T1189)) or interactively via [Command and Scripting Interpreter](https://attack.mitre.org/techniques/T1059).(Citation: Akamai JS)(Citation: Malware Monday VBE) For example, adversaries may abuse syntax that utilizes various symbols and escape characters (such as spacing, `^`, `+`. `$`, and `%`) to make commands difficult to analyze while maintaining the same intended functionality.(Citation: RC PowerShell) Many languages support built-in obfuscation in the form of base64 or URL encoding.(Citation: Microsoft PowerShellB64) Adversaries may also manually implement command obfuscation via string splitting (`“Wor”+“d.Application”`), order and casing of characters (`rev <<<'dwssap/cte/ tac'`), globing (`mkdir -p '/tmp/:&$NiA'`), as well as various tricks involving passing strings through tokens/environment variables/input streams.(Citation: Bashfuscator Command Obfuscators)(Citation: FireEye Obfuscation June 2017) Adversaries may also use tricks such as directory traversals to obfuscate references to the binary being invoked by a command (`C:\voi\pcw\..\..\Windows\tei\qs\k\..\..\..\system32\erool\..\wbem\wg\je\..\..\wmic.exe shadowcopy delete`).(Citation: Twitter Richard WMIC) Tools such as <code>Invoke-Obfuscation</code> and <code>Invoke-DOSfucation</code> have also been used to obfuscate commands.(Citation: Invoke-DOSfuscation)(Citation: Invoke-Obfuscation)