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CrimsonEDR is an open-source project engineered to identify specific malware patterns, offering a tool for honing skills in circumventing Endpoint Detection and Response (EDR). By leveraging diverse detection methods, it empowers users to deepen their understanding of security evasion tactics.
| Detection | Description |
|---|---|
| Direct Syscall | Detects the usage of direct system calls, often employed by malware to bypass traditional API hooks. |
| NTDLL Unhooking | Identifies attempts to unhook functions within the NTDLL library, a common evasion technique. |
| AMSI Patch | Detects modifications to the Anti-Malware Scan Interface (AMSI) through byte-level analysis. |
| ETW Patch | Detects byte-level alterations to Event Tracing for Windows (ETW), commonly manipulated by malware to evade detection. |
| PE Stomping | Identifies instances of PE (Portable Executable) stomping. |
| Reflective PE Loading | Detects the reflective loading of PE files, a technique employed by malware to avoid static analysis. |
| Unbacked Thread Origin | Identifies threads originating from unbacked memory regions, often indicative of malicious activity. |
| Unbacked Thread Start Address | Detects threads with start addresses pointing to unbacked memory, a potential sign of code injection. |
| API hooking | Places a hook on the NtWriteVirtualMemory function to monitor memory modifications. |
| Custom Pattern Search | Allows users to search for specific patterns provided in a JSON file, facilitating the identification of known malware signatures. |
To get started with CrimsonEDR, follow these steps:
FreshRSS 
bash sudo apt-get install gcc-mingw-w64-x86-64
bash git clone https://github.com/Helixo32/CrimsonEDR
bash cd CrimsonEDR; chmod +x compile.sh; ./compile.sh
Windows Defender and other antivirus programs may flag the DLL as malicious due to its content containing bytes used to verify if the AMSI has been patched. Please ensure to whitelist the DLL or disable your antivirus temporarily when using CrimsonEDR to avoid any interruptions.
To use CrimsonEDR, follow these steps:
ioc.json file is placed in the current directory from which the executable being monitored is launched. For example, if you launch your executable to monitor from C:\Users\admin\, the DLL will look for ioc.json in C:\Users\admin\ioc.json. Currently, ioc.json contains patterns related to msfvenom. You can easily add your own in the following format:{
"IOC": [
["0x03", "0x4c", "0x24", "0x08", "0x45", "0x39", "0xd1", "0x75"],
["0xf1", "0x4c", "0x03", "0x4c", "0x24", "0x08", "0x45", "0x39"],
["0x58", "0x44", "0x8b", "0x40", "0x24", "0x49", "0x01", "0xd0"],
["0x66", "0x41", "0x8b", "0x0c", "0x48", "0x44", "0x8b", "0x40"],
["0x8b", "0x0c", "0x48", "0x44", "0x8b", "0x40", "0x1c", "0x49"],
["0x01", "0xc1", "0x38", "0xe0", "0x75", "0xf1", "0x4c", "0x03"],
["0x24", "0x49", "0x01", "0xd0", "0x66", "0x41", "0x8b", "0x0c"],
["0xe8", "0xcc", "0x00", "0x00", "0x00", "0x41", "0x51", "0x41"]
]
}
Execute CrimsonEDRPanel.exe with the following arguments:
-d <path_to_dll>: Specifies the path to the CrimsonEDR.dll file.
-p <process_id>: Specifies the Process ID (PID) of the target process where you want to inject the DLL.
For example:
.\CrimsonEDRPanel.exe -d C:\Temp\CrimsonEDR.dll -p 1234
Here are some useful resources that helped in the development of this project:
For questions, feedback, or support, please reach out to me via:
py-amsi is a library that scans strings or files for malware using the Windows Antimalware Scan Interface (AMSI) API. AMSI is an interface native to Windows that allows applications to ask the antivirus installed on the system to analyse a file/string. AMSI is not tied to Windows Defender. Antivirus providers implement the AMSI interface to receive calls from applications. This library takes advantage of the API to make antivirus scans in python. Read more about the Windows AMSI API here.
Via pip
pip install pyamsi
Clone repository
git clone https://github.com/Tomiwa-Ot/py-amsi.git
cd py-amsi/
python setup.py installfrom pyamsi import Amsi
# Scan a file
Amsi.scan_file(file_path, debug=True) # debug is optional and False by default
# Scan string
Amsi.scan_string(string, string_name, debug=False) # debug is optional and False by default
# Both functions return a dictionary of the format
# {
# 'Sample Size' : 68, // The string/file size in bytes
# 'Risk Level' : 0, // The risk level as suggested by the antivirus
# 'Message' : 'File is clean' // Response message
# }| Risk Level | Meaning |
|---|---|
| 0 | AMSI_RESULT_CLEAN (File is clean) |
| 1 | AMSI_RESULT_NOT_DETECTED (No threat detected) |
| 16384 | AMSI_RESULT_BLOCKED_BY_ADMIN_START (Threat is blocked by the administrator) |
| 20479 | AMSI_RESULT_BLOCKED_BY_ADMIN_END (Threat is blocked by the administrator) |
| 32768 | AMSI_RESULT_DETECTED (File is considered malware) |
https://tomiwa-ot.github.io/py-amsi/index.html
MSI Dump - a tool that analyzes malicious MSI installation packages, extracts files, streams, binary data and incorporates YARA scanner.
On Macro-enabled Office documents we can quickly use oletools mraptor to determine whether document is malicious. If we want to dissect it further, we could bring in oletools olevba or oledump.
To dissect malicious MSI files, so far we had only one, but reliable and trustworthy lessmsi. However, lessmsi doesn't implement features I was looking for:
Hence this is where msidump comes into play.
This tool helps in quick triages as well as detailed examinations of malicious MSIs corpora. It lets us:
file/MIME type deduction to determine inner data typeIt was created as a companion tool to the blog post I released here:
WindowsInstaller.Installer interfaces, currently it is not possible to support native Linux platforms. Maybe wine python msidump.py could help, but haven't tried that yet.cmd> python msidump.py evil.msi -y rules.yara
Here we can see that input MSI is injected with suspicious VBScript and contains numerous executables in it.
We see from the triage table that it was present in Binary table. Lets get him:
python msidump.py putty-backdoored.msi -l binary -i UBXtHArj
We can specify which to record dump either by its name/ID or its index number (here that would be 7).
Lets have a look at another example. This time there is executable stored in Binary table that will be executed during installation:
To extract that file we're gonna go with
python msidump.py evil2.msi -x binary -i lmskBju -O extracted
Where
-x binary tells to extract contents of Binary table-i lmskBju specifies which record exactly to extract-O extracted sets output directoryFor the best output experience, run the tool on a maximized console window or redirect output to file:
python msidump.py [...] -o analysis.log
PS D:\> python .\msidump.py --help
options:
-h, --help show this help message and exit
Required arguments:
infile Input MSI file (or directory) for analysis.
Options:
-q, --quiet Surpress banner and unnecessary information. In triage mode, will display only verdict.
-v, --verbose Verbose mode.
-d, --debug Debug mode.
-N, --nocolor Dont use colors in text output.
-n PRINT_LEN, --print-len PRINT_LEN
When previewing data - how many bytes to include in preview/hexdump. Default: 128
-f {text,json,csv}, --format {text,json,csv}
Output format: text, json, csv. Default: text
-o path, --outfile path
Redirect program output to this file.
-m, --mime When sniffing inner data type, report MIME types
Analysis Modes:
-l what, --list what List specific table contents. See help message to learn what can be listed.
-x what, --extract what
Extract data from MSI. For what can be extracted, refer to help message.
Analysis Specific options:
-i number|name, --record number|name
Can be a number or name. In --list mode, specifies which record to dump/display entirely. In --extract mode dumps only this particular record to --outdir
-O path, --outdir path
When --extract mode is used, specifies output location where to extract data.
-y path, --yara path Path to YARA rule/directory with rules. YARA will be matched against Binary data, streams and inner files
------------------------------------------------------
- What can be listed:
--list CustomAction - Specific table
--lis t Registry,File - List multiple tables
--list stats - Print MSI database statistics
--list all - All tables and their contents
--list olestream - Prints all OLE streams & storages.
To display CABs embedded in MSI try: --list _Streams
--list cabs - Lists embedded CAB files
--list binary - Lists binary data embedded in MSI for its own purposes.
That typically includes EXEs, DLLs, VBS/JS scripts, etc
- What can be extracted:
--extract all - Extracts Binary data, all files from CABs, scripts from CustomActions
--extract binary - Extracts Binary data
--extract files - Extracts files
--extract cabs - Extracts cabinets
--extract scripts - Extrac ts scripts
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CustomAction Types based on assessing their numbers, which is prone to being evaded. Apparently when naming my tool, I didn't think on checking whether it was already taken. There is another tool named msidump being part of msitools GNU package:
This and other projects are outcome of sleepless nights and plenty of hard work. If you like what I do and appreciate that I always give back to the community, Consider buying me a coffee (or better a beer) just to say thank you!
Mariusz Banach / mgeeky, (@mariuszbit)
<mb [at] binary-offensive.com>
