Scanner for Simple Indicators of Compromise
Detection is based on four detection methods:
- File Name IOC
Regex match on full file path/name
- Yara Rule Check
Yara signature match on file data and process memory
- Hash check
Compares known malicious hashes (MD5, SHA1, SHA256) with scanned files
- C2 Back Connect Check
Compares process connection endpoints with C2 IOCs (new since version v.10)
- Regin filesystem check (via –reginfs)
- Process anomaly check (based on Sysforensics)
- SWF decompressed scan (new since version v0.8)
- SAM dump check
- DoublePulsar check – tries to detect DoublePulsar backdoor on port 445/tcp and 3389/tcp
- PE-Sieve process check
The Windows binary is compiled with PyInstaller 2.1 and should run as x86 application on both x86 and x64 based systems.
Download the latest version of LOKI from the releases section.
How-To Run LOKI and Analyse the Reports
- Download the latest LOKI version from the releases section
- Run it once to retrieve the latest signature base repository
- Provide the folder to a target system that should be scanned: removable media, network share, folder on target system
- Right-click on loki.exe and select “Run as Administrator” or open a command line “cmd.exe” as Administrator and run it from there (you can also run LOKI without administrative privileges but some checks will be disabled and relevant objects on disk will not be accessible)
- The resulting report will show a GREEN, YELLOW or RED result line.
- Please analyse the findings yourself by:
- uploading non-confidential samples to Virustotal.com
- Search the web for the filename
- Search the web for keywords from the rule name (e.g. EQUATIONGroupMalware_1 > search for “Equation Group”)
- Search the web for the MD5 hash of the sample
- Search in my customer APT search engine for file names or identifiers
- Please report back false positives via the Issues section (mention the false positive indicator like a hash and/or filename and the rule name that triggered)
Since version 0.21.0 LOKI includes a separate updater tool named
usage: loki-upgrader.py [-h] [-l log-file] [--sigsonly] [--progonly] [--nolog] [--debug] Loki - Upgrader optional arguments: -h, --help show this help message and exit -l log-file Log file --sigsonly Update the signatures only --progonly Update the program files only --nolog Don't write a local log file --debug Debug output
It allows to update the compiled loki.exe for Windows and the signature-base sources.
loki.exe --update it will create an new upgrader process and exits LOKI in order to replace the
loki.exe with the newer one, which would be locked otherwise.
usage: loki.exe [-h] [-p path] [-s kilobyte] [-l log-file] [-r remote-loghost] [-a alert-level] [-w warning-level] [-n notice-level] [--printAll] [--allreasons] [--noprocscan] [--nofilescan] [--scriptanalysis] [--rootkit] [--noindicator] [--reginfs] [--dontwait] [--intense] [--csv] [--onlyrelevant] [--nolog] [--update] [--debug] Loki - Simple IOC Scanner optional arguments: -h, --help show this help message and exit -p path Path to scan -s kilobyte Maximum file size to check in KB (default 5000 KB) -l log-file Log file -r remote-loghost Remote syslog system -a alert-level Alert score -w warning-level Warning score -n notice-level Notice score --printAll Print all files that are scanned --allreasons Print all reasons that caused the score --noprocscan Skip the process scan --nofilescan Skip the file scan --scriptanalysis Activate script analysis (beta) --rootkit Skip the rootkit check --noindicator Do not show a progress indicator --reginfs Do check for Regin virtual file system --dontwait Do not wait on exit --intense Intense scan mode (also scan unknown file types and all extensions) --csv Write CSV log format to STDOUT (machine processing) --onlyrelevant Only print warnings or alerts --nolog Don't write a local log file --update Update the signatures from the "signature-base" sub repository --debug Debug output
No requirements if you use the pre-compiled executables in the
release section of this repo.
If you want to build LOKI yourself:
- yara : just use the latest release source code, compile and install it (or install it via pip install yara-python)
- Some Python packages: pip install yara-python psutil netaddr pylzma colorama
- yara : It’s recommended to use the most recent version of the compiled packages for Windows (e.g. yara-python-18.104.22.168.win32-py2.7.exe – Download it from here
- pywin32 : path conversions (PyInstaller issue; Windows only)
- Microsoft Visual C++ 2010 Redistributable Package (here)
- Microsoft Visual C++ Compiler for Python 2.7 (here): for pylzma
c:\Python27[-x64]\python.exe -m pip install --upgrade pip pip.exe install psutil netaddr wmi colorama pylzma pycrypto yara-python pywin32 rfc5424-logging-handler setuptools==19.2 pyinstaller==2.1
Package LOKI with a Private Rule Set
LOKI can be packaged with a custom encrypted rule set, which is embedded in the pyinstaller package. In order to include your own rules place them in a directory named
private-signatures in the LOKI directory and execute
loki/ ├── private-signatures/ <-- YARA rules places in here will by added to loki.exe ├── signature-base/ <-- clear text and still required (retrieved by loki-upgrader.exe) │ ├── iocs/ │ ├── yara/
In order to successfully run the build script, you need to install PyInstaller. We use PyInstaller 2.1 due the problem that Packages build with PyInstaller 3 don’t run on Windows 2003 and XP based systems. (yes, we need that in incident response – there are even productive systems out there running Windows 2000 or Windows NT)
The easiest way to do install PyInstaller is:
pip install pyinstaller==2.1
After that, you can just run the build script.
You can verify whether the signature set is valid by calling
C:\Python27[-x64]\python.exe loki-package-builder.py --ruledir signatures --target rules
The usage of this tool is:
usage: loki-package-builder.py [-h] --ruledir RULEDIR --target TARGET Package builder for Loki optional arguments: -h, --help show this help message and exit --ruledir RULEDIR directory containing the rules to build into Loki --target TARGET target where to store the compiled ruleset
Requirements for the Threat Intel Receivers
Signature and IOCs
Since version 0.15 the Yara signatures reside in the sub-repository signature-base. You can just download the LOKI release ZIP archive and run LOKI once to download the ‘signature-base’ sub repository with all the signatures. Since version 0.21.0 a separate updater is provided as
loki-upgrader.py. LOKI expects the IOCs and signatures of the
signature-base repo in a subfolder named
The IOC files for hashes and filenames are stored in the ‘./signature-base/iocs’ folder. All ‘.yar’ files placed in the ‘./signature-base/yara’ folder will be initialized together with the rule set that is already included. Use the ‘score’ value to define the level of the message upon a signature match.
You can add hash, c2 and filename IOCs by adding files to the ‘./signature-base/iocs’ subfolder. All hash IOCs and filename IOC files must be in the format used by LOKI (see the default files). The files must have the strings “hash”, “filename” or “c2” in their name to get pulled during initialization.
For Hash IOCs (divided by newline; hash type is detected automatically)
For Filename IOCs (divided by newline)
# Description [Reference] Regex;Score;False Positive Regex
You can use the following external variables in the YARA rules that your provide to LOKI:
filename - e.g. condition: $s1 and not filename == 'nmap.exe' filepath - e.g. condition: filepath == 'C:\Windows\cmd.exe' extension - e.g. condition: uint32(0) == 0x5a4d and extension == ".txt" filetype - eg. condition: extension == ".txt" and filetype == "EXE" (see file-type-signatures.cfg in signature-base repo for all detected file types) md5 - legacy value
User-Defined Scan Excludes
Since version v0.16.2 LOKI supports the definition of user-defined excludes via “excludes.cfg” in the new “./config” folder. Each line represents a regular expression thats gets applied to the full file path during the directory walk. This way you can exclude certain directories regardless of their drive name or file extensions in certain folders and all files and directories that belong to a product that is sensitive to antivirus scanning.
The ”’exclude.cfg”’ looks like this:
# Excluded directories # # - add directories you want to exclude from the scan # - double escape back slashes # - values are case-insensitive # - remember to use back slashes on Windows and slashes on Linux / Unix / OSX # - each line contains a regex that matches somewhere in the full path (case insensitive) # e.g.: # Regex: \\System32\\ # Matches C:\Windows\System32\cmd.exe # # Regex: /var/log/[^/]+\.log # Matches: /var/log/test.log # Not Matches: /var/log/test.gz # # Useful examples \\Ntfrs\\ \\Ntds\\ \\EDB[^\.]+\.log Sysvol\\Staging\\Nntfrs_cmp \\System Volume Information\\DFSR
Since version 0.26 LOKI integrates @hasherezade’s great tool PE-Sieve to detect process anomalies.
The tool is initialized if LOKI finds it in the
./tools sub folder during startup.
Threat Intel Receivers
Since version v0.10 LOKI includes various threat intel receivers using the public APIs of these services to retrieve and store the IOCs in a format that LOKI understands. It is no problem if these indicators overlap with the ones already included. Loki uses a filename regex or hash only once. (no performance impact)
The threat intel receivers have also been moved to the signature-base sub repository with version 0.15 and can be found in “./signature-base/threatintel”.
Provide your API key via
-k APIKEY or set it in the script header.
Open Threat Exchange (OTX) Receiver
It’s a simple script that downloads your subscribed events/iocs from Alienvault OTX and stores them in the correct format in the ‘./iocs’ subfolder. The script is located in the “./threatintel” folder and is named “get-otx-iocs.py”. (see requirements above)
usage: get-otx-iocs.py [-h] [-k APIKEY] [-o dir] [--verifycert] [--debug] OTX IOC Receiver optional arguments: -h, --help show this help message and exit -k APIKEY OTX API key -o dir Output directory --verifycert Verify the server certificate --debug Debug output
A simple script that downloads your subscribed events/iocs from a custom MISP instance and stores them in the correct format in the ‘./iocs’ subfolder. YARA rules stored in MISP will be written to the ‘./iocs/yara’ subfolder and automatically initialized during startup. The script is located in the “./threatintel” folder and is named “get-misp-iocs.py”. (see requirements above)
usage: get-misp-iocs.py [-h] [-u URL] [-k APIKEY] [-l tframe] [-o dir] [-y yara-dir] [--verifycert] [--debug] MISP IOC Receiver optional arguments: -h, --help show this help message and exit -u URL MISP URL -k APIKEY MISP API key -l tframe Time frame (e.g. 2d, 12h - default=30d) -o dir Output directory -y yara-dir YARA rule output directory --verifycert Verify the server certificate --debug Debug output
Command Line Scan Output
Hash based IOCs
File Name based IOCs
Generated log file
Compile the Scanner
Download PyInstaller v2.1, switch to the pyinstaller program directory and execute:
python ./pyinstaller.py -F C:\path\to\loki.py
This will create a
loki.exe in the subfolder
To include the msvcr100.dll to improve the target os compatibility change the line in the file
./loki/loki.spec that contains
a.binaries, to the following:
a.binaries + [('msvcr100.dll', 'C:\Windows\System32\msvcr100.dll', 'BINARY')],
Use LOKI on Mac OS X
- Download Yara sources from here
- Install openssl (brew install openssl, then sudo cp -r /usr/local/Cellar/openssl/1.0.2h_1/include /usr/local)
- sudo make install
- Change to folder
python setup.py install
- Also install the requirements,
sudo pip install coloramagitpython, netaddr, pylzma etc…
- Download and unpack this into Loki folder
- cd loki folder, sudo python loki.py -p /
Antivirus – False Positives
The compiled scanner may be detected by antivirus engines. This is caused by the fact that the scanner is a compiled python script that implement some file system and process scanning features that are also used in compiled malware code.
If you don’t trust the compiled executable, please compile it yourself.
Loki (this link opens in a new window) by Neo23x0 (this link opens in a new window)
Loki – Simple IOC and Incident Response Scanner