Sub-technique of T1027 Obfuscated Files or Information.View on attack.mitre.org
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).
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.
File archives may be sent as one Spearphishing Attachment 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). 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.
Compression may be used in combination with Encrypted/Encoded File where compressed files are encrypted and password-protected.
Rules on DetectionCode tagged with T1027.015.
None recorded.
| Used by | Procedure example |
|---|---|
| GroupGamaredon Group | Gamaredon Group has delivered malicious payloads within compressed archives and zip files. |
| GroupHigaisa | Higaisa used Base64 encoded compressed payloads. |
| GroupKimsuky | Kimsuky has delivered malicious payloads within Zip archives. |
| GroupLeviathan | Leviathan has obfuscated code using gzip compression. |
| GroupMofang | Mofang has compressed the ShimRat executable within malicious email attachments. |
| GroupMolerats | Molerats has delivered compressed executables within ZIP files to victims. |
| GroupTA2541 | TA2541 has used compressed and char-encoded scripts in operations. |
| GroupThreat Group-3390 | Threat Group-3390 malware is compressed with LZNT1 compression. |
| Used by | Procedure example |
|---|---|
| MalwareBADHATCH | BADHATCH can be compressed with the ApLib algorithm. |
| MalwareDarkWatchman | DarkWatchman has been delivered as compressed RAR payloads in ZIP files to victims. |
| ToolDonut | Donut can generate encrypted, compressed/encoded, or otherwise obfuscated code modules. |
| MalwareGelsemium | Gelsemium has the ability to compress its components. |
| MalwareHancitor | Hancitor has delivered compressed payloads in ZIP files to victims. |
| MalwareHermeticWiper | HermeticWiper can compress 32-bit and 64-bit driver files with the Lempel-Ziv algorithm. |
| MalwareKerrdown | Kerrdown can encrypt, encode, and compress multiple layers of shellcode. |
| MalwareLine Runner | Line Runner uses a ZIP payload that is automatically extracted with its contents, a LUA script, executed for initial execution via CVE-2024-20359. |
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