Usage

Following types of executable files are supported:

• for Portable executable (PE) files use JetBrains.FormatRipper.Pe.PeFile
• for Compound files or MS Windows Installer compound (MSI) files use JetBrains.FormatRipper.Compound.CompoundFile
• for ELF files use JetBrains.FormatRipper.Elf.ElfFile
• for Mach-O/Fat-Mach-O use JetBrains.FormatRipper.MachO.MachOFile

The client code should detect the file type and create an appropriate object to use.

File type detection

In order to detect the file type JetBrains.FormatRipper.FileExplorer.FileTypeExplorer can be used.

using var stream = File.OpenRead(pathToFile);
var res = stream.DetectFileType();
System.Console.WriteLine($"{res.FileType}: {res.FileProperties}"); // Pe: SharedLibraryType, Managed, Signed

Signature verification

Signature verification parameters

In order to verify the signature of any supported executable the client code should create the SignatureVerificationParams object and pass is to the call of VerifySignatureAsync method.

SignatureVerificationParams constructor apply following parameters:

• signRootCertStore - Stream of PKCS #7 store with CA certificates for which a chain will be build and validate
• timestampRootCertStore - Stream of PKCS #7 store with a timestamp CA certificates for which a chain will be build and validate
• buildChain - If true, build and verify a certificates chain (by default true)
• withRevocationCheck - If true, verify a revocation status for certificates in all chains (apply if buildChain is true, by default true)
• ocspResponseTimeout - Timeout for OCSP request (5 sec. by default, apply if withRevocationCheck is true)
• signatureValidationTimeMode - Mode of selection time which is used for certificates and CRLs validation (Timestamp by default)
• signatureValidationTime - Time which is used when signatureValidationTimeMode has SignValidationTime value

The timestamp CA certificates may be included in the separate PKCS#7 store file, and passed to the timestampRootCertStore parameter.

Certificate revocation status checking is performed when withRevocationCheck is true. The check is based on CRLs, but if it is not available, OCSP is used.

Example

static Task Main(string[] args)
{
    var pathToMachO = args[0];
    var pathToPe = args[1];
    var logger = new SimpleConsoleLogger();
    return ResourceUtil.OpenDefaultRoots(async defaultRootsStream =>
        {
            var verificationParams = new SignatureVerificationParams(
                signRootCertStore: defaultRootsStream,
                timestampRootCertStore: null,
                buildChain: true,
                withRevocationCheck: false);
            await VerifyMachO(logger, pathToMachO, verificationParams);
            await VerifyPe(logger, pathToPe, verificationParams);
        });
}

static async Task VerifyMachO(ILogger logger, string path, SignatureVerificationParams verificationParams)
{
    using var stream = File.OpenRead(path);
    var file = MachOFile.Parse(stream, MachOFile.Mode.SignatureData);
    foreach (var section in file.Sections)
    {
        var result = await VerifySignature(logger, section.SignatureData, verificationParams);
        DisplayResult(logger, result);
    }
}

static async Task VerifyPe(ILogger logger, string path, SignatureVerificationParams verificationParams)
{
    using var stream = File.OpenRead(path);
    var file = PeFile.Parse(stream, PeFile.Mode.SignatureData);
    VerifySignatureResult result = await VerifySignature(logger, file.SignatureData, verificationParams);
    DisplayResult(logger, result);
}

static async Task<VerifySignatureResult> VerifySignature(ILogger logger, SignatureData signatureData, SignatureVerificationParams verificationParams)
{
    var signedMessage = SignedMessage.CreateInstance(signatureData);
    var signedMessageVerifier = new SignedMessageVerifier(logger);
    return await signedMessageVerifier.VerifySignatureAsync(signedMessage, verificationParams);
}

static void DisplayResult(ILogger logger, VerifySignatureResult result)
{
    if (result.Status == VerifySignatureStatus.Valid)
        logger.Info("Signature is VALID!");
    else
        logger.Error($"Signature is INVALID! {result.Message}");
}

Hash computing

Following hashing algorithms are supported:

• MD5
• SHA1
• SHA256
• SHA384
• SHA512

In order to compute hash of the executable call the HashUtil.ComputeHash() method.

Example

using var stream = File.OpenRead(pathToFile);
var file = PeFile.Parse(stream, PeFile.Mode.ComputeHashInfo);
var hash = HashUtil.ComputeHash(stream, file.ComputeHashInfo, HashAlgorithmName.SHA512);

Additional

Example of logger

class SimpleConsoleLogger : ILogger
{
   public void Info(string str) => System.Console.WriteLine($"INFO: {str}");
   public void Warning(string str) => System.Console.Error.WriteLine($"WARNING: {str}");
   public void Error(string str) => System.Console.Error.WriteLine($"ERROR: {str}");
   public void Trace(string str) => System.Console.Error.WriteLine($"TRACE: {str}");
}

Default CA certificates

The library contains the JetBrains.SignatureVerifier.ResourceUtil.OpenDefaultRoots() method which returns the stream of the PKCS#7 store with following root certificates: