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Strelka is a real-time, container-based file scanning system used for threat hunting, threat detection, and incident response. Originally based on the design established by Lockheed Martin's Laika BOSS and similar projects (see: related projects), Strelka's purpose is to perform file extraction and metadata collection at enterprise scale.
Strelka differs from its sibling projects in a few significant ways:
- Core codebase is Go and Python3.9+
- Server components run in containers for ease and flexibility of deployment
- OS-native client applications for Windows, Mac, and Linux
- Built using libraries and formats that allow cross-platform, cross-language support
Features
Strelka is a modular data scanning platform, allowing users or systems to submit files for the purpose of analyzing, extracting, and reporting file content and metadata. Coupled with a SIEM, Strelka is able to aggregate, alert, and provide analysts with the capability to better understand their environment without having to perform direct data gathering or time-consuming file analysis.
Quickstart
Running a file through Strelka is simple. In this section, Strelka capabilities of extraction and analysis are demonstrated for a one-off analysis.
Please review the documentation for details on how to properly build and deploy Strelka in an enterprise environment.
Step 1: Install prerequisites
# Ubuntu 22.04
sudo apt install -y wget git docker docker-compose golang jq && \
sudo usermod -aG docker $USER && \
newgrp dockerStep 2: Download Strelka
git clone https://github.com/target/strelka.git && \
cd strelkaStep 3: Download and install preferred yara rules (optional)
rm configs/python/backend/yara/rules.yara && \
git clone https://github.com/Yara-Rules/rules.git configs/python/backend/yara/rules/ && \
echo 'include "./rules/index.yar"' > configs/python/backend/yara/rules.yaraStep 4a: Pull precompiled images and start Strelka
Note: You can skip the go build process and use the Strelka UI at http://0.0.0.0:9980 to analyze files.
docker-compose -f build/docker-compose-no-build.yaml up -d && \
go build github.com/target/strelka/src/go/cmd/strelka-oneshotStep 4b: Build and start Strelka
Note: You can skip the go build process and use the Strelka UI at http://0.0.0.0:9980 to analyze files.
docker-compose -f build/docker-compose.yaml build && \
docker-compose -f build/docker-compose.yaml up -d && \
go build github.com/target/strelka/src/go/cmd/strelka-oneshotStep 5: Prepare a file to analyze
Use any malware sample, or other file you'd like Strelka to analyze.
wget https://github.com/ytisf/theZoo/raw/master/malware/Binaries/Win32.Emotet/Win32.Emotet.zip -P samples/Step 6: Analyze the file with Strelka using the dockerized oneshot
./strelka-oneshot -f samples/Win32.Emotet.zip -l - | jqWhat's happening here?
- Strelka determined that the submitted file was an encrypted ZIP (See: taste.yara backend.yaml)
- ScanEncryptedZip used a dictionary to crack the ZIP file password, and extract the compressed file
- The extracted file was sent back into the Strelka pipeline by the scanner, and Strelka determined that the extracted file was an EXE
- ScanPe dissected the EXE file and added useful metadata to the output
- ScanYara analyzed the EXE file, using the provided rules, and added numerous matches to the output, some indicating the file might be malicious
The following output has been edited for brevity.
{
"file": {
"depth": 0,
"flavors": {
"mime": ["application/zip"],
"yara": ["encrypted_zip", "zip_file"]
},
"scanners": [
"ScanEncryptedZip",
"ScanEntropy",
"ScanFooter",
"ScanHash",
"ScanHeader",
"ScanYara",
"ScanZip"
]
},
"scan": {
"encrypted_zip": {
"cracked_password": "infected",
"elapsed": 0.114269,
"total": {"extracted": 1, "files": 1}
}
}
}{
"file": {
"depth": 1,
"flavors": {
"mime": ["application/x-dosexec"],
"yara": ["mz_file"]
},
"name": "29D6161522C7F7F21B35401907C702BDDB05ED47.bin",
"scanners": [
"ScanEntropy",
"ScanFooter",
"ScanHash",
"ScanHeader",
"ScanPe",
"ScanYara"
]
},
"scan": {
"pe": {
"address_of_entry_point": 5168,
"base_of_code": 4096,
"base_of_data": 32768,
"checksum": 47465,
"compile_time": "2015-03-31T08:53:51",
"elapsed": 0.013076,
"file_alignment": 4096,
"file_info": {
"company_name": "In CSS3",
"file_description": "Note: In CSS3, the text-decoration property is a shorthand property for text-decoration-line, text-decoration-color, and text-decoration-style, but this is currently.",
"file_version": "1.00.0065",
"fixed": {"operating_systems": ["WINDOWS32"]},
"internal_name": "Callstb",
"original_filename": "NOFAstb.exe",
"product_name": "Goodreads",
"product_version": "1.00.0065",
"var": {"character_set": "Unicode", "language": "U.S. English"}
}
},
"yara": {
"elapsed": 0.068918,
"matches": [
"SEH__vba",
"SEH_Init",
"Big_Numbers1",
"IsPE32",
"IsWindowsGUI",
"HasOverlay",
"HasRichSignature",
"Microsoft_Visual_Basic_v50v60",
"Microsoft_Visual_Basic_v50",
"Microsoft_Visual_Basic_v50_v60",
"Microsoft_Visual_Basic_v50_additional",
"Microsoft_Visual_Basic_v50v60_additional"
],
"tags": [
"AntiDebug",
"SEH",
"Tactic_DefensiveEvasion",
"Technique_AntiDebugging",
"SubTechnique_SEH",
"PECheck",
"PEiD"
]
}
}
}What's next?
If Strelka was deployed and ingesting files in your environment, you might be collecting these events in your SIEM. With this analysis, you could write a rule that looks for events matching the suspicious yara tags, alerting you to a potentially malicious file.
scan.yara.tags:("Technique_AntiDebugging" && "SubTechnique_SEH")
Fileshot UI
Strelka's UI is available when you build the provided containers. This web interface allows you to upload files to Strelka and capture the events, which are stored locally.
Navigate to http://localhost:9980/ and use the login strelka/strelka.
Potential Uses
With over 50 file scanners for the most common file types (e.g., exe, docx, js, zip), Strelka provides users with the ability to gain new insights into files on their host, network, or enterprise. While Strelka is not a detection engine itself (although it does utilize YARA, it can provide enough metadata to identify suspicious or malicious files. Some potential uses for Strelka include:
Additional Documentation
More documentation about Strelka can be found in the README, including:
Contribute
Guidelines for contributing can be found here.
Known Issues
See issues labeled bug in the tracker for any potential known issues.
Related Projects
Licensing
Strelka and its associated code is released under the terms of the Apache 2.0 License.
