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A command line Windows API tracing tool for Golang binaries.
Note: This tool is a PoC and a work-in-progress prototype so please treat it as such. Feedbacks are always welcome!
Although Golang programs contains a lot of nuances regarding the way they are built and their behavior in runtime they still need to interact with the OS layer and that means at some point they do need to call functions from the Windows API.
The Go runtime package contains a function called asmstdcall and this function is a kind of "gateway" used to interact with the Windows API. Since it's expected this function to call the Windows API functions we can assume it needs to have access to information such as the address of the function and it's parameters, and this is where things start to get more interesting.
Asmstdcall receives a single parameter which is pointer to something similar to the following structure:
FreshRSS struct LIBCALL {
DWORD_PTR Addr;
DWORD Argc;
DWORD_PTR Argv;
DWORD_PTR ReturnValue;
[...]
}
Some of these fields are filled after the API function is called, like the return value, others are received by asmstdcall, like the function address, the number of arguments and the list of arguments. Regardless when those are set it's clear that the asmstdcall function manipulates a lot of interesting information regarding the execution of programs compiled in Golang.
The gftrace leverages asmstdcall and the way it works to monitor specific fields of the mentioned struct and log it to the user. The tool is capable of log the function name, it's parameters and also the return value of each Windows function called by a Golang application. All of it with no need to hook a single API function or have a signature for it.
The tool also tries to ignore all the noise from the Go runtime initialization and only log functions called after it (i.e. functions from the main package).
If you want to know more about this project and research check the blogpost.
Download the latest release.
gftrace.exe <filepath> <params>
All you need to do is specify which functions you want to trace in the gftrace.cfg file, separating it by comma with no spaces:
CreateFileW,ReadFile,CreateProcessW
The exact Windows API functions a Golang method X of a package Y would call in a specific scenario can only be determined either by analysis of the method itself or trying to guess it. There's some interesting characteristics that can be used to determine it, for example, Golang applications seems to always prefer to call functions from the "Wide" and "Ex" set (e.g. CreateFileW, CreateProcessW, GetComputerNameExW, etc) so you can consider it during your analysis.
The default config file contains multiple functions in which I tested already (at least most part of them) and can say for sure they can be called by a Golang application at some point. I'll try to update it eventually.
Tracing CreateFileW() and ReadFile() in a simple Golang file that calls "os.ReadFile" twice:
- CreateFileW("C:\Users\user\Desktop\doc.txt", 0x80000000, 0x3, 0x0, 0x3, 0x1, 0x0) = 0x168 (360)
- ReadFile(0x168, 0xc000108000, 0x200, 0xc000075d64, 0x0) = 0x1 (1)
- CreateFileW("C:\Users\user\Desktop\doc2.txt", 0x80000000, 0x3, 0x0, 0x3, 0x1, 0x0) = 0x168 (360)
- ReadFile(0x168, 0xc000108200, 0x200, 0xc000075d64, 0x0) = 0x1 (1)
Tracing CreateProcessW() in the TunnelFish malware:
- CreateProcessW("C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe", "powershell /c "Add-PSSnapin Microsoft.Exchange.Management.PowerShell.SnapIn; Get-Recipient | Select Name -ExpandProperty EmailAddresses -first 1 | Select SmtpAddress | ft -hidetableheaders"", 0x0, 0x0, 0x1, 0x80400, "=C:=C:\Users\user\Desktop", 0x0, 0xc0000ace98, 0xc0000acd68) = 0x1 (1)
- CreateProcessW("C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe", "powershell /c "Add-PSSnapin Microsoft.Exchange.Management.PowerShell.SnapIn; Get-Recipient | Select Name -ExpandProperty EmailAddresses -first 1 | Select SmtpAddress | ft -hidetableheaders"", 0x0, 0x0, 0x1, 0x80400, "=C:=C:\Users\user\Desktop", 0x0, 0xc0000c4ec8, 0xc0000c4d98) = 0x1 (1)
- CreateProcessW("C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe", "powershell /c "Add-PSSnapin Microsoft.Exchange.Management.PowerShell.SnapIn; Get-Recipient | Select Name -ExpandProperty EmailAddresses -first 1 | Select SmtpAddres s | ft -hidetableheaders"", 0x0, 0x0, 0x1, 0x80400, "=C:=C:\Users\user\Desktop", 0x0, 0xc00005eec8, 0xc00005ed98) = 0x1 (1)
- CreateProcessW("C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe", "powershell /c "Add-PSSnapin Microsoft.Exchange.Management.PowerShell.SnapIn; Get-Recipient | Select Name -ExpandProperty EmailAddresses -first 1 | Select SmtpAddress | ft -hidetableheaders"", 0x0, 0x0, 0x1, 0x80400, "=C:=C:\Users\user\Desktop", 0x0, 0xc0000bce98, 0xc0000bcd68) = 0x1 (1)
- CreateProcessW("C:\WINDOWS\system32\cmd.exe", "cmd /c "wmic computersystem get domain"", 0x0, 0x0, 0x1, 0x80400, "=C:=C:\Users\user\Desktop", 0x0, 0xc0000c4ef0, 0xc0000c4dc0) = 0x1 (1)
- CreateProcessW("C:\WINDOWS\system32\cmd.exe", "cmd /c "wmic computersystem get domain"", 0x0, 0x0, 0x1, 0x80400, "=C:=C:\Users\user\Desktop", 0x0, 0xc0000acec0, 0xc0000acd90) = 0x1 (1)
- CreateProcessW("C:\WINDOWS\system32\cmd.exe", "cmd /c "wmic computersystem get domain"", 0x0, 0x0, 0x1, 0x80400, "=C:=C:\Users\user\Desktop", 0x0, 0xc0000bcec0, 0xc0000bcd90) = 0x1 (1)
[...]
Tracing multiple functions in the Sunshuttle malware:
- CreateFileW("config.dat.tmp", 0x80000000, 0x3, 0x0, 0x3, 0x1, 0x0) = 0xffffffffffffffff (-1)
- CreateFileW("config.dat.tmp", 0xc0000000, 0x3, 0x0, 0x2, 0x80, 0x0) = 0x198 (408)
- CreateFileW("config.dat.tmp", 0xc0000000, 0x3, 0x0, 0x3, 0x80, 0x0) = 0x1a4 (420)
- WriteFile(0x1a4, 0xc000112780, 0xeb, 0xc0000c79d4, 0x0) = 0x1 (1)
- GetAddrInfoW("reyweb.com", 0x0, 0xc000031f18, 0xc000031e88) = 0x0 (0)
- WSASocketW(0x2, 0x1, 0x0, 0x0, 0x0, 0x81) = 0x1f0 (496)
- WSASend(0x1f0, 0xc00004f038, 0x1, 0xc00004f020, 0x0, 0xc00004eff0, 0x0) = 0x0 (0)
- WSARecv(0x1f0, 0xc00004ef60, 0x1, 0xc00004ef48, 0xc00004efd0, 0xc00004ef18, 0x0) = 0xffffffff (-1)
- GetAddrInfoW("reyweb.com", 0x0, 0xc000031f18, 0xc000031e88) = 0x0 (0)
- WSASocketW(0x2, 0x1, 0x0, 0x0, 0x0, 0x81) = 0x200 (512)
- WSASend(0x200, 0xc00004f2b8, 0x1, 0xc00004f2a0, 0x0, 0xc00004f270, 0x0) = 0x0 (0)
- WSARecv(0x200, 0xc00004f1e0, 0x1, 0xc00004f1c8, 0xc00004f250, 0xc00004f198, 0x0) = 0xffffffff (-1)
[...]
Tracing multiple functions in the DeimosC2 framework agent:
- WSASocketW(0x2, 0x1, 0x0, 0x0, 0x0, 0x81) = 0x130 (304)
- setsockopt(0x130, 0xffff, 0x20, 0xc0000b7838, 0x4) = 0xffffffff (-1)
- socket(0x2, 0x1, 0x6) = 0x138 (312)
- WSAIoctl(0x138, 0xc8000006, 0xaf0870, 0x10, 0xb38730, 0x8, 0xc0000b746c, 0x0, 0x0) = 0x0 (0)
- GetModuleFileNameW(0x0, "C:\Users\user\Desktop\samples\deimos.exe", 0x400) = 0x2f (47)
- GetUserProfileDirectoryW(0x140, "C:\Users\user", 0xc0000b7a08) = 0x1 (1)
- LookupAccountSidw(0x0, 0xc00000e250, "user", 0xc0000b796c, "DESKTOP-TEST", 0xc0000b7970, 0xc0000b79f0) = 0x1 (1)
- NetUserGetInfo("DESKTOP-TEST", "user", 0xa, 0xc0000b7930) = 0x0 (0)
- GetComputerNameExW(0x5, "DESKTOP-TEST", 0xc0000b7b78) = 0x1 (1)
- GetAdaptersAddresses(0x0, 0x10, 0x0, 0xc000120000, 0xc0000b79d0) = 0x0 (0)
- CreateToolhelp32Snapshot(0x2, 0x0) = 0x1b8 (440)
- GetCurrentProcessId() = 0x2584 (9604)
- GetCurrentDirectoryW(0x12c, "C:\Users\user\AppData\Local\Programs\retoolkit\bin") = 0x39 (57 )
[...]
The gftrace is published under the GPL v3 License. Please refer to the file named LICENSE for more information.
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:
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:
