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Restore CS 4.0 "encrypted" methods

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This commit is contained in:
de4dot 2012-04-22 14:16:33 +02:00
parent 59e2e51882
commit c9f63a5866
2 changed files with 166 additions and 74 deletions
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40
de4dot.code/deobfuscators/CliSecure/CliSecureRtType.cs
View File

@ -19,6 +19,7 @@
using System;
using Mono.Cecil;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.CliSecure {
class CliSecureRtType {
@ -73,7 +74,12 @@ namespace de4dot.code.deobfuscators.CliSecure {
public void find() {
if (cliSecureRtType != null)
return;
if (find2())
return;
findOld();
}
bool find2() {
foreach (var type in module.Types) {
if (type.Namespace != "")
continue;
@ -111,8 +117,40 @@ namespace de4dot.code.deobfuscators.CliSecure {
postInitializeMethod = postInitialize;
loadMethod = load;
cliSecureRtType = type;
return;
return true;
}
return false;
}
bool findOld() {
var methodToCheck = DotNetUtils.getModuleTypeCctor(module);
if (methodToCheck == null)
return false;
foreach (var calledMethod in DotNetUtils.getCalledMethods(module, methodToCheck)) {
var type = calledMethod.DeclaringType;
if (!hasPinvokeMethod(type, "_Initialize"))
continue;
if (!hasPinvokeMethod(type, "_Initialize64"))
continue;
initializeMethod = calledMethod;
cliSecureRtType = type;
return true;
}
return false;
}
static bool hasPinvokeMethod(TypeDefinition type, string methodName) {
foreach (var method in type.Methods) {
if (method.PInvokeInfo == null)
continue;
if (method.PInvokeInfo.EntryPoint == methodName)
return true;
}
return false;
}
}
}

200
de4dot.code/deobfuscators/CliSecure/MethodsDecrypter.cs
View File

@ -19,14 +19,11 @@
using System;
using System.Collections.Generic;
using System.IO;
using Mono.MyStuff;
using de4dot.PE;
namespace de4dot.code.deobfuscators.CliSecure {
[Serializable]
class InvalidDecryptedMethod : Exception {
}
class CodeHeader {
public byte[] signature;
public byte[] decryptionKey;
@ -60,7 +57,22 @@ namespace de4dot.code.deobfuscators.CliSecure {
IDecrypter decrypter;
interface IDecrypter {
byte[] decrypt(MethodInfo methodInfo);
byte[] decrypt(MethodInfo methodInfo, out byte[] extraSections);
}
class DoNothingDecrypter : IDecrypter {
PeImage peImage;
public DoNothingDecrypter(PeImage peImage) {
this.peImage = peImage;
}
public byte[] decrypt(MethodInfo methodInfo, out byte[] extraSections) {
peImage.Reader.BaseStream.Position = methodInfo.codeOffs;
byte[] code;
MethodBodyParser.parseMethodBody(peImage.Reader, out code, out extraSections);
return code;
}
}
abstract class DecrypterBase : IDecrypter {
@ -74,36 +86,11 @@ namespace de4dot.code.deobfuscators.CliSecure {
endOfMetadata = peImage.rvaToOffset(peImage.Cor20Header.metadataDirectory.virtualAddress + peImage.Cor20Header.metadataDirectory.size);
}
public abstract byte[] decrypt(MethodInfo methodInfo);
public abstract byte[] decrypt(MethodInfo methodInfo, out byte[] extraSections);
protected static byte[] getCodeBytes(byte[] methodBody) {
int codeOffset, codeSize;
switch ((methodBody[0] & 3)) {
case 2:
codeOffset = 1;
codeSize = methodBody[0] >> 2;
break;
case 3:
codeOffset = 4 * (methodBody[1] >> 4);
if (codeOffset != 12)
throw new InvalidDecryptedMethod();
codeSize = BitConverter.ToInt32(methodBody, 4);
uint lsig = BitConverter.ToUInt32(methodBody, 8);
if (lsig != 0 && (lsig >> 24) != 0x11)
throw new InvalidDecryptedMethod();
break;
default:
throw new InvalidDecryptedMethod();
}
if (codeSize + codeOffset > methodBody.Length)
throw new InvalidDecryptedMethod();
var code = new byte[codeSize];
Array.Copy(methodBody, codeOffset, code, 0, codeSize);
protected byte[] getCodeBytes(byte[] methodBody, out byte[] extraSections) {
byte[] code;
MethodBodyParser.parseMethodBody(new BinaryReader(new MemoryStream(methodBody)), out code, out extraSections);
return code;
}
}
@ -113,7 +100,7 @@ namespace de4dot.code.deobfuscators.CliSecure {
: base(peImage, codeHeader) {
}
public override byte[] decrypt(MethodInfo methodInfo) {
public override byte[] decrypt(MethodInfo methodInfo, out byte[] extraSections) {
byte[] data = peImage.offsetReadBytes(endOfMetadata + methodInfo.codeOffs, (int)methodInfo.codeSize);
for (int i = 0; i < data.Length; i++) {
byte b = data[i];
@ -121,7 +108,7 @@ namespace de4dot.code.deobfuscators.CliSecure {
b ^= codeHeader.decryptionKey[(methodInfo.codeOffs - 0x30 + i + 7) % 16];
data[i] = b;
}
return getCodeBytes(data);
return getCodeBytes(data, out extraSections);
}
}
@ -135,7 +122,7 @@ namespace de4dot.code.deobfuscators.CliSecure {
key[i] = be_readUint32(codeHeader.decryptionKey, i * 4);
}
public override byte[] decrypt(MethodInfo methodInfo) {
public override byte[] decrypt(MethodInfo methodInfo, out byte[] extraSections) {
byte[] data = peImage.offsetReadBytes(endOfMetadata + methodInfo.codeOffs, (int)methodInfo.codeSize);
int numQwords = (int)(methodInfo.codeSize / 8);
@ -156,7 +143,7 @@ namespace de4dot.code.deobfuscators.CliSecure {
be_writeUint32(data, offset + 4, q1);
}
return getCodeBytes(data);
return getCodeBytes(data, out extraSections);
}
static uint be_readUint32(byte[] data, int offset) {
@ -174,12 +161,84 @@ namespace de4dot.code.deobfuscators.CliSecure {
}
}
interface ICsHeader {
List<MethodInfo> getMethodInfos(uint codeHeaderOffset);
void patchMethodDefTable(MetadataType methodDefTable, IList<MethodInfo> methodInfos);
uint getMethodBodyOffset(MethodInfo methodInfo, uint methodDefElemOffset);
}
// CS 5.2+
class CsHeader5 : ICsHeader {
MethodsDecrypter methodsDecrypter;
public CsHeader5(MethodsDecrypter methodsDecrypter) {
this.methodsDecrypter = methodsDecrypter;
}
public List<MethodInfo> getMethodInfos(uint codeHeaderOffset) {
uint offset = codeHeaderOffset + methodsDecrypter.codeHeader.totalCodeSize + 0x30;
var methodInfos = new List<MethodInfo>((int)methodsDecrypter.codeHeader.numMethods);
for (int i = 0; i < (int)methodsDecrypter.codeHeader.numMethods; i++, offset += 16) {
uint codeOffs = methodsDecrypter.peImage.offsetReadUInt32(offset);
uint codeSize = methodsDecrypter.peImage.offsetReadUInt32(offset + 4);
uint flags = methodsDecrypter.peImage.offsetReadUInt32(offset + 8);
uint localVarSigTok = methodsDecrypter.peImage.offsetReadUInt32(offset + 12);
methodInfos.Add(new MethodInfo(codeOffs, codeSize, flags, localVarSigTok));
}
return methodInfos;
}
public void patchMethodDefTable(MetadataType methodDefTable, IList<MethodInfo> methodInfos) {
uint offset = methodDefTable.fileOffset - methodDefTable.totalSize;
foreach (var methodInfo in methodInfos) {
offset += methodDefTable.totalSize;
if (methodInfo.flags == 0 || methodInfo.codeOffs == 0)
continue;
uint rva = methodsDecrypter.peImage.offsetReadUInt32(offset);
methodsDecrypter.peImage.writeUint16(rva, (ushort)methodInfo.flags);
methodsDecrypter.peImage.writeUint32(rva + 8, methodInfo.localVarSigTok);
}
}
public uint getMethodBodyOffset(MethodInfo methodInfo, uint methodDefElemOffset) {
return methodsDecrypter.peImage.rvaToOffset(methodsDecrypter.peImage.offsetReadUInt32(methodDefElemOffset));
}
}
// CS 4.0
class CsHeader4 : ICsHeader {
MethodsDecrypter methodsDecrypter;
public CsHeader4(MethodsDecrypter methodsDecrypter) {
this.methodsDecrypter = methodsDecrypter;
}
public List<MethodInfo> getMethodInfos(uint codeHeaderOffset) {
uint offset = codeHeaderOffset + methodsDecrypter.codeHeader.totalCodeSize + 0x28;
var methodInfos = new List<MethodInfo>((int)methodsDecrypter.codeHeader.numMethods);
for (int i = 0; i < (int)methodsDecrypter.codeHeader.numMethods; i++, offset += 4) {
uint codeOffs = methodsDecrypter.peImage.offsetReadUInt32(offset);
if (codeOffs != 0)
codeOffs += codeHeaderOffset;
methodInfos.Add(new MethodInfo(codeOffs, 0, 0, 0));
}
return methodInfos;
}
public void patchMethodDefTable(MetadataType methodDefTable, IList<MethodInfo> methodInfos) {
}
public uint getMethodBodyOffset(MethodInfo methodInfo, uint methodDefElemOffset) {
return methodInfo.codeOffs;
}
}
public bool decrypt(PeImage peImage, string filename, CliSecureRtType csRtType, ref DumpedMethods dumpedMethods) {
this.peImage = peImage;
try {
return decrypt2(ref dumpedMethods);
}
catch (InvalidDecryptedMethod) {
catch (InvalidMethodBody) {
Log.w("Using dynamic method decryption");
byte[] moduleCctorBytes = getModuleCctorBytes(csRtType);
dumpedMethods = de4dot.code.deobfuscators.MethodsDecrypter.decrypt(filename, moduleCctorBytes);
@ -202,30 +261,37 @@ namespace de4dot.code.deobfuscators.CliSecure {
return moduleCctorBytes;
}
bool isOldHeader(MetadataType methodDefTable) {
if (methodDefTable.totalSize != codeHeader.methodDefElemSize)
return true;
if (methodDefTable.fileOffset - peImage.rvaToOffset(peImage.Cor20Header.metadataDirectory.virtualAddress) != codeHeader.methodDefTableOffset)
return true;
return false;
}
ICsHeader createCsHeader(MetadataType methodDefTable) {
if (isOldHeader(methodDefTable)) {
decrypter = new DoNothingDecrypter(peImage);
return new CsHeader4(this);
}
return new CsHeader5(this);
}
public bool decrypt2(ref DumpedMethods dumpedMethods) {
uint offset = peImage.rvaToOffset(peImage.Cor20Header.metadataDirectory.virtualAddress + peImage.Cor20Header.metadataDirectory.size);
if (!readCodeHeader(offset))
uint codeHeaderOffset = peImage.rvaToOffset(peImage.Cor20Header.metadataDirectory.virtualAddress + peImage.Cor20Header.metadataDirectory.size);
if (!readCodeHeader(codeHeaderOffset))
return false;
var metadataTables = peImage.Cor20Header.createMetadataTables();
var methodDefTable = metadataTables.getMetadataType(MetadataIndex.iMethodDef);
if (methodDefTable.totalSize != codeHeader.methodDefElemSize)
return false;
var methodInfos = getMethodInfos(offset + 0x30 + codeHeader.totalCodeSize);
offset = methodDefTable.fileOffset - methodDefTable.totalSize;
foreach (var methodInfo in methodInfos) {
offset += methodDefTable.totalSize;
if (methodInfo.flags == 0 || methodInfo.codeOffs == 0)
continue;
uint rva = peImage.offsetReadUInt32(offset);
peImage.writeUint16(rva, (ushort)methodInfo.flags);
peImage.writeUint32(rva + 8, methodInfo.localVarSigTok);
}
var csHeader = createCsHeader(methodDefTable);
var methodInfos = csHeader.getMethodInfos(codeHeaderOffset);
csHeader.patchMethodDefTable(methodDefTable, methodInfos);
dumpedMethods = new DumpedMethods();
offset = methodDefTable.fileOffset;
uint offset = methodDefTable.fileOffset;
for (int i = 0; i < methodInfos.Count; i++, offset += methodDefTable.totalSize) {
var methodInfo = methodInfos[i];
if (methodInfo.codeOffs == 0)
@ -234,26 +300,26 @@ namespace de4dot.code.deobfuscators.CliSecure {
var dm = new DumpedMethod();
dm.token = 0x06000001 + (uint)i;
uint rva = peImage.offsetReadUInt32(offset);
uint methodBodyOffset = csHeader.getMethodBodyOffset(methodInfo, offset);
dm.mdImplFlags = peImage.offsetReadUInt16(offset + (uint)methodDefTable.fields[1].offset);
dm.mdFlags = peImage.offsetReadUInt16(offset + (uint)methodDefTable.fields[2].offset);
dm.mdName = peImage.offsetRead(offset + (uint)methodDefTable.fields[3].offset, methodDefTable.fields[3].size);
dm.mdSignature = peImage.offsetRead(offset + (uint)methodDefTable.fields[4].offset, methodDefTable.fields[4].size);
dm.mdParamList = peImage.offsetRead(offset + (uint)methodDefTable.fields[5].offset, methodDefTable.fields[5].size);
dm.code = decrypter.decrypt(methodInfo);
dm.code = decrypter.decrypt(methodInfo, out dm.extraSections);
if ((peImage.readByte(rva) & 3) == 2) {
if ((peImage.offsetReadByte(methodBodyOffset) & 3) == 2) {
dm.mhFlags = 2;
dm.mhMaxStack = 8;
dm.mhCodeSize = (uint)dm.code.Length;
dm.mhLocalVarSigTok = 0;
}
else {
dm.mhFlags = peImage.readUInt16(rva);
dm.mhMaxStack = peImage.readUInt16(rva + 2);
dm.mhFlags = peImage.offsetReadUInt16(methodBodyOffset);
dm.mhMaxStack = peImage.offsetReadUInt16(methodBodyOffset + 2);
dm.mhCodeSize = (uint)dm.code.Length;
dm.mhLocalVarSigTok = peImage.readUInt32(rva + 8);
dm.mhLocalVarSigTok = peImage.offsetReadUInt32(methodBodyOffset + 8);
}
dumpedMethods.add(dm);
@ -284,17 +350,5 @@ namespace de4dot.code.deobfuscators.CliSecure {
return true;
}
List<MethodInfo> getMethodInfos(uint offset) {
var methodInfos = new List<MethodInfo>((int)codeHeader.numMethods);
for (int i = 0; i < (int)codeHeader.numMethods; i++, offset += 16) {
uint codeOffs = peImage.offsetReadUInt32(offset);
uint codeSize = peImage.offsetReadUInt32(offset + 4);
uint flags = peImage.offsetReadUInt32(offset + 8);
uint localVarSigTok = peImage.offsetReadUInt32(offset + 12);
methodInfos.Add(new MethodInfo(codeOffs, codeSize, flags, localVarSigTok));
}
return methodInfos;
}
}
}