521 lines
14 KiB
C#
521 lines
14 KiB
C#
/*
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Copyright (C) 2011-2015 de4dot@gmail.com
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This file is part of de4dot.
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de4dot is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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de4dot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with de4dot. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Text.RegularExpressions;
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using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.DeepSea {
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class AssemblyResolver : ResolverBase {
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Version version;
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List<FieldInfo> fieldInfos;
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MethodDef decryptMethod;
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enum Version {
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Unknown,
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V3Old,
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V3,
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V4,
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V404,
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V41,
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V41SL,
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}
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public class AssemblyInfo {
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public byte[] data;
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public string fullName;
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public string simpleName;
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public string extension;
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public EmbeddedResource resource;
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public AssemblyInfo(byte[] data, string fullName, string simpleName, string extension, EmbeddedResource resource) {
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this.data = data;
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this.fullName = fullName;
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this.simpleName = simpleName;
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this.extension = extension;
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this.resource = resource;
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}
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public override string ToString() {
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return fullName;
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}
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}
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class FieldInfo {
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public FieldDef field;
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public int magic;
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public FieldInfo(FieldDef field, int magic) {
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this.field = field;
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this.magic = magic;
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}
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}
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public MethodDef DecryptMethod {
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get { return decryptMethod; }
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}
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public AssemblyResolver(ModuleDefMD module, ISimpleDeobfuscator simpleDeobfuscator, IDeobfuscator deob)
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: base(module, simpleDeobfuscator, deob) {
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}
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static string[] requiredLocals_sl = new string[] {
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"System.Byte[]",
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"System.IO.Stream",
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"System.Reflection.Assembly",
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"System.Security.Cryptography.SHA1Managed",
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"System.Windows.AssemblyPart",
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};
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protected override bool CheckResolverInitMethodSilverlight(MethodDef resolverInitMethod) {
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if (resolverInitMethod.Body.ExceptionHandlers.Count != 1)
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return false;
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foreach (var method in DotNetUtils.GetCalledMethods(module, resolverInitMethod)) {
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if (!method.IsStatic || method.Body == null)
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continue;
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if (!method.IsPublic || method.HasGenericParameters)
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continue;
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if (!DotNetUtils.IsMethod(method, "System.Void", "(System.String)"))
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continue;
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simpleDeobfuscator.Deobfuscate(method);
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if (!new LocalTypes(method).All(requiredLocals_sl))
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continue;
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initMethod = resolverInitMethod;
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resolveHandler = method;
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UpdateVersion(resolveHandler);
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return true;
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}
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return false;
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}
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void UpdateVersion(MethodDef handler) {
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if (IsV3Old(handler)) {
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version = Version.V3Old;
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return;
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}
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if (IsV3SL(handler)) {
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version = Version.V3; // 3.x-4.0.4
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return;
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}
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if (IsV41SL(handler)) {
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version = Version.V41SL;
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return;
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}
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}
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static bool IsV3SL(MethodDef handler) {
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var instrs = handler.Body.Instructions;
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for (int i = 0; i < instrs.Count - 3; i++) {
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if (!instrs[i].IsLdloc())
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continue;
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if (instrs[i + 1].OpCode.Code != Code.Add)
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continue;
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if (!instrs[i + 2].IsLdcI4())
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continue;
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if (instrs[i + 3].OpCode.Code != Code.And)
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continue;
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return true;
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}
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return false;
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}
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static bool IsV41SL(MethodDef handler) {
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var instrs = handler.Body.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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if (!instrs[i].IsLdcI4() || instrs[i].GetLdcI4Value() != 5)
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continue;
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if (instrs[i + 1].OpCode.Code != Code.And)
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continue;
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if (!instrs[i + 2].IsLdcI4() || instrs[i + 2].GetLdcI4Value() != 0x1F)
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continue;
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if (instrs[i + 3].OpCode.Code != Code.And)
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continue;
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return true;
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}
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return false;
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}
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static bool IsV3Old(MethodDef method) {
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return DotNetUtils.CallsMethod(method, "System.Int32 System.IO.Stream::Read(System.Byte[],System.Int32,System.Int32)") &&
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!DotNetUtils.CallsMethod(method, "System.Int32 System.IO.Stream::ReadByte()") &&
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// Obfuscated System.Int32 System.IO.Stream::ReadByte()
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!DotNetUtils.CallsMethod(method, "System.Int32", "(System.IO.Stream,System.Int32,System.Int32)");
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}
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protected override bool CheckResolverInitMethodInternal(MethodDef resolverInitMethod) {
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return DotNetUtils.CallsMethod(resolverInitMethod, "System.Void System.AppDomain::add_AssemblyResolve(System.ResolveEventHandler)");
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}
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protected override bool CheckHandlerMethodDesktopInternal(MethodDef handler) {
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if (CheckHandlerV3(handler) || checkHandlerSL(handler)) {
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UpdateVersion(handler);
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return true;
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}
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simpleDeobfuscator.Deobfuscate(handler);
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List<FieldInfo> fieldInfosTmp;
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MethodDef decryptMethodTmp;
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if (CheckHandlerV4(handler, out fieldInfosTmp, out decryptMethodTmp)) {
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version = Version.V4;
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fieldInfos = fieldInfosTmp;
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decryptMethod = decryptMethodTmp;
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return true;
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}
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Version versionTmp = CheckHandlerV404_41(handler, out fieldInfosTmp, out decryptMethodTmp);
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if (fieldInfosTmp.Count != 0) {
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version = versionTmp;
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fieldInfos = fieldInfosTmp;
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decryptMethod = decryptMethodTmp;
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return true;
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}
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return false;
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}
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static string[] handlerLocalTypes_NET = new string[] {
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"System.Byte[]",
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"System.IO.Compression.DeflateStream",
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"System.IO.MemoryStream",
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"System.IO.Stream",
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"System.Reflection.Assembly",
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"System.Security.Cryptography.SHA1CryptoServiceProvider",
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"System.String",
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};
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static bool CheckHandlerV3(MethodDef handler) {
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return new LocalTypes(handler).All(handlerLocalTypes_NET);
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}
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static string[] handlerLocalTypes_SL = new string[] {
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"System.Byte[]",
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"System.IO.Stream",
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"System.Reflection.Assembly",
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"System.Security.Cryptography.SHA1Managed",
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"System.String",
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"System.Windows.AssemblyPart",
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};
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static bool checkHandlerSL(MethodDef handler) {
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return new LocalTypes(handler).All(handlerLocalTypes_SL);
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}
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// 4.0.1.18 .. 4.0.3
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bool CheckHandlerV4(MethodDef handler, out List<FieldInfo> fieldInfos, out MethodDef decryptMethod) {
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fieldInfos = new List<FieldInfo>();
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decryptMethod = null;
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var instrs = handler.Body.Instructions;
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for (int i = 0; i < instrs.Count - 3; i++) {
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int index = i;
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var ldtoken = instrs[index++];
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if (ldtoken.OpCode.Code != Code.Ldtoken)
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continue;
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var field = ldtoken.Operand as FieldDef;
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if (field == null || field.InitialValue == null || field.InitialValue.Length == 0)
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return false;
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var ldci4_len = instrs[index++];
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if (!ldci4_len.IsLdcI4())
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return false;
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if (ldci4_len.GetLdcI4Value() != field.InitialValue.Length)
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return false;
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var ldci4_magic = instrs[index++];
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if (!ldci4_magic.IsLdcI4())
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return false;
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int magic = ldci4_magic.GetLdcI4Value();
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var call = instrs[index++];
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if (call.OpCode.Code == Code.Tailcall)
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call = instrs[index++];
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if (call.OpCode.Code != Code.Call)
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return false;
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var decryptMethodTmp = call.Operand as MethodDef;
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if (!DotNetUtils.IsMethod(decryptMethodTmp, "System.Reflection.Assembly", "(System.RuntimeFieldHandle,System.Int32,System.Int32)"))
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return false;
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decryptMethod = decryptMethodTmp;
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fieldInfos.Add(new FieldInfo(field, magic));
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}
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return fieldInfos.Count != 0;
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}
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// 4.0.4, 4.1+
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Version CheckHandlerV404_41(MethodDef handler, out List<FieldInfo> fieldInfos, out MethodDef decryptMethod) {
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Version version = Version.Unknown;
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fieldInfos = new List<FieldInfo>();
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decryptMethod = null;
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var instrs = handler.Body.Instructions;
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for (int i = 0; i < instrs.Count - 6; i++) {
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int index = i;
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var ldci4_len = instrs[index++];
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if (!ldci4_len.IsLdcI4())
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continue;
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if (instrs[index++].OpCode.Code != Code.Newarr)
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continue;
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if (!instrs[index++].IsStloc())
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continue;
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if (!instrs[index++].IsLdloc())
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continue;
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var ldtoken = instrs[index++];
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if (ldtoken.OpCode.Code != Code.Ldtoken)
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continue;
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var field = ldtoken.Operand as FieldDef;
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if (field == null || field.InitialValue == null || field.InitialValue.Length == 0)
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continue;
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var call1 = instrs[index++];
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if (call1.OpCode.Code != Code.Call)
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continue;
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if (!DotNetUtils.IsMethod(call1.Operand as IMethod, "System.Void", "(System.Array,System.RuntimeFieldHandle)"))
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continue;
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int callIndex = GetCallDecryptMethodIndex(instrs, index);
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if (callIndex < 0)
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continue;
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var args = DsUtils.GetArgValues(instrs, callIndex);
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if (args == null)
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continue;
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var decryptMethodTmp = instrs[callIndex].Operand as MethodDef;
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if (decryptMethodTmp == null)
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continue;
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int magic;
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Version versionTmp;
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GetMagic(decryptMethodTmp, args, out versionTmp, out magic);
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version = versionTmp;
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decryptMethod = decryptMethodTmp;
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fieldInfos.Add(new FieldInfo(field, magic));
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}
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return version;
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}
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static bool GetMagic(MethodDef method, IList<object> args, out Version version, out int magic) {
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magic = 0;
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int magicIndex = GetMagicIndex(method, out version);
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if (magicIndex < 0 || magicIndex >= args.Count)
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return false;
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var val = args[magicIndex];
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if (!(val is int))
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return false;
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magic = (int)val;
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return true;
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}
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static int GetMagicIndex(MethodDef method, out Version version) {
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int magicIndex = GetMagicIndex404(method);
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if (magicIndex >= 0) {
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version = Version.V404;
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return magicIndex;
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}
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magicIndex = GetMagicIndex41Trial(method);
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if (magicIndex >= 0) {
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version = Version.V41;
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return magicIndex;
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}
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version = Version.Unknown;
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return -1;
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}
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static int GetMagicIndex404(MethodDef method) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 4; i++) {
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int index = i;
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if (!instrs[index++].IsLdloc())
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continue;
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var ldarg = instrs[index++];
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if (!ldarg.IsLdarg())
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continue;
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if (instrs[index++].OpCode.Code != Code.Add)
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continue;
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var ldci4 = instrs[index++];
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if (!ldci4.IsLdcI4())
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continue;
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if (ldci4.GetLdcI4Value() != 0xFF)
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continue;
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return ldarg.GetParameterIndex();
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}
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return -1;
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}
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static int GetMagicIndex41Trial(MethodDef method) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 4; i++) {
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int index = i;
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if (instrs[index++].OpCode.Code != Code.Div)
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continue;
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var ldarg = instrs[index++];
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if (!ldarg.IsLdarg())
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continue;
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if (instrs[index++].OpCode.Code != Code.Add)
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continue;
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var ldci4 = instrs[index++];
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if (!ldci4.IsLdcI4())
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continue;
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if (ldci4.GetLdcI4Value() != 0xFF)
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continue;
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return ldarg.GetParameterIndex();
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}
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return -1;
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}
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static int GetCallDecryptMethodIndex(IList<Instruction> instrs, int index) {
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index = GetRetIndex(instrs, index);
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if (index < 0)
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return -1;
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for (int i = index - 1; i >= 0; i--) {
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var instr = instrs[i];
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if (!IsCallOrNext(instr))
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break;
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if (instr.OpCode.Code != Code.Call)
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continue;
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var calledMethod = instr.Operand as IMethod;
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if (calledMethod == null || calledMethod.MethodSig.GetParamCount() < 2)
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continue;
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return i;
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}
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return -1;
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}
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static int GetRetIndex(IList<Instruction> instrs, int index) {
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for (int i = index; i < instrs.Count; i++) {
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var instr = instrs[i];
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if (instr.OpCode.Code == Code.Ret)
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return i;
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if (!IsCallOrNext(instr))
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break;
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}
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return -1;
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}
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static bool IsCallOrNext(Instruction instr) {
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switch (instr.OpCode.FlowControl) {
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case FlowControl.Call:
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case FlowControl.Next:
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return true;
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default:
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return false;
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}
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}
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public IEnumerable<AssemblyInfo> GetAssemblyInfos() {
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if (!Detected)
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return new List<AssemblyInfo>();
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switch (version) {
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case Version.V3Old:
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return GetAssemblyInfos(resource => DecryptResourceV3Old(resource));
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case Version.V3:
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return GetAssemblyInfos(resource => DecryptResourceV3(resource));
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case Version.V4:
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case Version.V404:
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return GetAssemblyInfosV4();
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case Version.V41:
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return GetAssemblyInfosV41();
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case Version.V41SL:
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return GetAssemblyInfos(resource => DecryptResourceV41SL(resource));
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default:
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throw new ApplicationException("Unknown version");
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}
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}
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IEnumerable<AssemblyInfo> GetAssemblyInfos(Func<EmbeddedResource, byte[]> decrypter) {
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var infos = new List<AssemblyInfo>();
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foreach (var tmp in module.Resources) {
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var resource = tmp as EmbeddedResource;
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if (resource == null)
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continue;
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if (!Regex.IsMatch(resource.Name.String, @"^[0-9A-F]{40}$"))
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continue;
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var info = GetAssemblyInfo(resource, decrypter);
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if (info == null)
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continue;
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infos.Add(info);
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}
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return infos;
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}
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AssemblyInfo GetAssemblyInfo(EmbeddedResource resource, Func<EmbeddedResource, byte[]> decrypter) {
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try {
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var decrypted = decrypter(resource);
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return GetAssemblyInfo(decrypted, resource);
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}
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catch (Exception) {
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return null;
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}
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}
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AssemblyInfo GetAssemblyInfo(byte[] decryptedData, EmbeddedResource resource) {
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var asm = AssemblyDef.Load(decryptedData);
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var fullName = asm.FullName;
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var simpleName = asm.Name.String;
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var extension = DeobUtils.GetExtension(asm.Modules[0].Kind);
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return new AssemblyInfo(decryptedData, fullName, simpleName, extension, resource);
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}
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IEnumerable<AssemblyInfo> GetAssemblyInfos(Func<byte[], int, byte[]> decrypter) {
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var infos = new List<AssemblyInfo>();
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if (fieldInfos == null)
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return infos;
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foreach (var fieldInfo in fieldInfos) {
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var decrypted = decrypter(fieldInfo.field.InitialValue, fieldInfo.magic);
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infos.Add(GetAssemblyInfo(decrypted, null));
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fieldInfo.field.InitialValue = new byte[1];
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fieldInfo.field.FieldSig.Type = module.CorLibTypes.Byte;
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fieldInfo.field.RVA = 0;
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}
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return infos;
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}
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IEnumerable<AssemblyInfo> GetAssemblyInfosV4() {
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return GetAssemblyInfos((data, magic) => DecryptResourceV4(data, magic));
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}
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IEnumerable<AssemblyInfo> GetAssemblyInfosV41() {
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return GetAssemblyInfos((data, magic) => InflateIfNeeded(Decrypt41Trial(data, magic)));
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}
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static byte[] Decrypt41Trial(byte[] data, int magic) {
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for (int i = 0; i < data.Length; i++)
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data[i] ^= (byte)(i / 3 + magic);
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return data;
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}
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}
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}
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