Opening COOS Files

The COOS file type is primarily associated with Multiple decryption tools.

COOS	File extension: COOS
	File type:	encrypted container

What is a COOS file?

COOS files mostly belong to Multiple decryption tools.

COOS Files Explained

The COOS file extension is used for files that store encrypted or obfuscated data in a variety of internal formats. Depending on the content, a COOS file may protect an image, a document, an executable, or even a compressed office file.
When the file contains an image, it often uses a JPG structure where the image and its metadata are encrypted or obfuscated. In other cases, the file holds a PDF document that is the output of an Optical Character Recognition process, securing text and layout.
Some COOS files are encrypted Windows executables. These files are known as an Overlay COntrol Structure file and are associated with security tools such as Cobalt Strike (visit Cobalt Strike).
Other variants include compressed office documents built with ZIP compression, linked to systems like Cisco Orbital Data Extractor (more details), or even files that simply contain ciphertext without an obvious internal format.
Use the appropriate decryption or extraction tool based on the internal file type to open and view the content.

Encrypted Images: JPG-based content with hidden metadata.
Document Files: PDF files produced from OCR processes.
Encrypted Executables: Windows EXE files using an overlay control structure.
Compressed Office Documents: ZIP-based files securing office data.
Generic Encrypted Files: Files that simply contain ciphertext.

How to open a COOS file

You need a suitable software like Multiple decryption tools to open a COOS file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your COOS file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a COOS file directly in the browser:. Just drag the file onto this browser window and drop it.

Online COOS Text Viewer

Choose your .coos file to analyze

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Online File Viewer

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Programs that open and convert COOS files:

Multiple decryption tools
See the previous paragraphs to learn more about the main application. COOS files are often referred to as Multiple decryption tools encodeds because this type of file is primarily created or used by this software.
Cobalt Strike
Files with the *.COOS extension are primarily associated with Cobalt Strike, a penetration testing tool. These COOS files, representing a small percentage of all files with this extension, contain an encrypted Windows executable often obfuscated using packers like Themida. They serve as the core component of Cobalt Strike's Overlay COntrol Structure, facilitating command and control operations during penetration testing exercises. This file format is classified as Encrypted Executable.

COOS format details:

The file format, which is the arrangement and type of data in a file, determines which program can open the file. The initial characters of a file are called signature, sometimes also referred to as "magic bytes". The signature can be used to infer the file format. Frequently, however, one file extension is used by different programs for different file formats, and one file format for different file extensions. Exact knowledge of the format is therefore important in order to solve problems occurring in files. Below is our analysis of the COOS files:

The COOS file extension is rather rarely used and includes different formats for different programs. But the following two file formats are common:

25% of all COOS files save the data in JPG file format. JPEG is the standard image format for lossy and compressed image data. The contents of these files cannot be read by a human; only a computer program can interpret the data. The files are on average 490 KB in size and range from 50 KB to 4 MB. The file type was created recently. Examples of file names are 20180601.jpg.coos. Such COOS files store data about bihar and paint.
15% of all COOS files save the data in PDF file format. PDF is short for Portable Document Format, is a file format to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. These files are binary files, so they do not contain text, but only cryptic characters. The files are 130 KB to 4 MB in size, with a median of 1 MB.

The remaining 60% of all COOS files are files with no common format, the following 7 formats can be found: EXE, ZIP, RAR and PNG. Files like these are sometimes linked to docx, xlsx, list or logo. Drag & drop your file here to see the file format and a preview of your COOS file!

Technical Data for COOS File Extension

File classification:

Encoded

Related files:

coo, cos, jpg, bin, file, ext, jpeg, pdf, exe, zip, docx

a coos encrypted container is a special file format and should only be edited and saved with the appropriate software.

How to solve problems with COOS files

Associate the COOS file extension with the correct application.
Update your software that should actually open encrypted containers. Because only the current version supports the latest COOS file format. Search, therefore, e.g. on the manufacturer website after an available Multiple decryption tools update.
To make sure that your COOS file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
Click here to open your .COOS file online - secure, fast, and no downloads needed.