Didier Stevens

Windows executables (PE files) can be signed on Kali using osslsigncode.

osslsigncode needs to be installed:

apt install osslsigncode

Then you need a certificate. For this demo, I’m using a self-signed cert.

The command to sign file demo-x64.exe with the demo certificate using SHA1 and timestamping, is:

osslsigncode sign -certs cert-20180729-110705.crt -key key-20180729-110705.pem -t http://timestamp.globalsign.com/scripts/timestamp.dll -in demo-x64.exe -out demo-x64-signed.exe

The signed file is demo-x64-signed.exe

To dual sign this executable (add SHA256 signature), use this command:

osslsigncode sign -certs cert-20180729-110705.crt -key key-20180729-110705.pem -t http://timestamp.globalsign.com/?signature=sha2 -h sha256 -nest -in demo-x64-signed.exe -out demo-x64-dual-signed.exe

The signed file is demo-x64-dual-signed.exe

Of course, Windows reports the signatures as invalid, because we used a self-signed certificate. For a valid signature, you can add your certificate to the trusted root certificates store, buy a code-signing certificate, …

For single SHA256 signing, use the second osslsigncode command without option -nest.

Quickpost info

To compile a Windows executable with version information and an icon on Kali, we use MinGW again.

The version information and icon (demo.ico) we want to use are defined in a resource file (demo.rc):

#include "winver.h"


#define IDI_ICON1                       101

/////////////////////////////////////////////////////////////////////////////
//
// Version
//

#define VER_FILEVERSION             0,0,0,1
#define VER_FILEVERSION_STR         "0.0.0.1\0"

#define VER_PRODUCTVERSION          0,0,0,1
#define VER_PRODUCTVERSION_STR      "0.0.0.1\0"

#ifndef DEBUG
#define VER_DEBUG                   0
#else
#define VER_DEBUG                   VS_FF_DEBUG
#endif

VS_VERSION_INFO VERSIONINFO
FILEVERSION     VER_FILEVERSION
PRODUCTVERSION  VER_PRODUCTVERSION
FILEFLAGSMASK   VS_FFI_FILEFLAGSMASK
FILEFLAGS       VER_DEBUG
FILEOS          VOS__WINDOWS32
FILETYPE        VFT_APP
FILESUBTYPE     VFT2_UNKNOWN
BEGIN
    BLOCK "StringFileInfo"
    BEGIN
        BLOCK "040904E4"
        BEGIN
            VALUE "CompanyName", "example.com"
            VALUE "FileDescription", "demo"
            VALUE "FileVersion", VER_FILEVERSION_STR
            VALUE "InternalName", "demo.exe"
            VALUE "LegalCopyright", "Public domain"
            VALUE "OriginalFilename", "demo.exe"
            VALUE "ProductName", "demo"
            VALUE "ProductVersion", VER_PRODUCTVERSION_STR
        END
    END
    BLOCK "VarFileInfo"
    BEGIN
        VALUE "Translation", 0x409, 1252
    END
END


/////////////////////////////////////////////////////////////////////////////
//
// Icon
//

// Icon with lowest ID value placed first to ensure application icon
// remains consistent on all systems.
IDI_ICON1               ICON                    "demo.ico"
/////////////////////////////////////////////////////////////////////////////

More info on the VERSIONINFO resource can be found here.
We use the resource compiler windres, and then the gcc compiler.

Compile for 64-bit:

x86_64-w64-mingw32-windres demo.rc demo-resource-x64.o
x86_64-w64-mingw32-gcc -o demo-x64.exe demo-resource-x64.o demo.c

Compile for 32-bit:

i686-w64-mingw32-windres demo.rc demo-resource-x86.o
i686-w64-mingw32-gcc -o demo-x86.exe demo-resource-x86.o demo.c

DemoResource_V_0_0_0_1.zip (https)
MD5: 9104DDC70264A9C2397258F292CC8FE4
SHA256: 722B3B52BAE6C675852A4AC728C08DBEEF4EC9C96F81229EF36E30FB54DC49DE

Quickpost info

MinGW is not only available on Kali, of course, but also on Windows. Compiling a DLL is very similar.

MinGW is installed in folder C:\msys64 on my machine.

To compile 64-bit executables, you need to start the 64-bit shell first: launch C:\msys64\mingw64.exe

Then you can compile the DLL:

gcc -shared -o DemoDll-x64.dll DemoDll.cpp

For 32-bit executables, it’s the 32-bit shell: launch C:\msys64\mingw32.exe

Then you can compile the DLL:

gcc -shared -o DemoDll-x86.dll DemoDll.cpp

It’s also possible to start the shell and compile from a BAT file:

call C:\msys64\msys2_shell.cmd -mingw64 -here -c "gcc -shared -o DemoDll-x64.dll DemoDll.cpp"
call C:\msys64\msys2_shell.cmd -mingw32 -here -c "gcc -shared -o DemoDll-x86.dll DemoDll.cpp"

Quickpost info