232 lines
6.3 KiB
C#
232 lines
6.3 KiB
C#
/*
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Copyright (C) 2011-2012 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.Collections.Generic;
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using dot10.DotNet;
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using dot10.DotNet.Emit;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.SmartAssembly {
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abstract class ResolverInfoBase {
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protected ModuleDefMD module;
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ISimpleDeobfuscator simpleDeobfuscator;
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IDeobfuscator deob;
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TypeDef resolverType;
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MethodDef callResolverMethod;
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public TypeDef Type {
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get { return resolverType; }
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}
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public TypeDef CallResolverType {
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get {
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if (callResolverMethod == null)
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return null;
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if (!hasOnlyThisMethod(callResolverMethod.DeclaringType, callResolverMethod))
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return null;
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return callResolverMethod.DeclaringType;
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}
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}
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public MethodDef CallResolverMethod {
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get { return callResolverMethod; }
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}
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public ResolverInfoBase(ModuleDefMD module, ISimpleDeobfuscator simpleDeobfuscator, IDeobfuscator deob) {
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this.module = module;
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this.simpleDeobfuscator = simpleDeobfuscator;
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this.deob = deob;
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}
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public bool findTypes() {
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if (resolverType != null)
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return true;
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if (findTypes(DotNetUtils.getModuleTypeCctor(module)))
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return true;
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if (findTypes(module.EntryPoint))
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return true;
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return false;
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}
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bool findTypes(MethodDef initMethod) {
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if (initMethod == null)
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return false;
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foreach (var method in DotNetUtils.getCalledMethods(module, initMethod)) {
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if (method.Name == ".cctor" || method.Name == ".ctor")
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continue;
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if (!method.IsStatic || !DotNetUtils.isMethod(method, "System.Void", "()"))
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continue;
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if (checkAttachAppMethod(method))
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return true;
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}
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return false;
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}
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bool checkAttachAppMethod(MethodDef attachAppMethod) {
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callResolverMethod = null;
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if (!attachAppMethod.HasBody)
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return false;
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foreach (var method in DotNetUtils.getCalledMethods(module, attachAppMethod)) {
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if (attachAppMethod == method)
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continue;
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if (method.Name == ".cctor" || method.Name == ".ctor")
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continue;
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if (!method.IsStatic || !DotNetUtils.isMethod(method, "System.Void", "()"))
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continue;
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if (!checkResolverInitMethod(method))
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continue;
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callResolverMethod = attachAppMethod;
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return true;
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}
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if (hasLdftn(attachAppMethod)) {
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simpleDeobfuscator.deobfuscate(attachAppMethod);
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foreach (var resolverHandler in getResolverHandlers(attachAppMethod)) {
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if (!resolverHandler.HasBody)
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continue;
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var resolverTypeTmp = getResolverType(resolverHandler);
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if (resolverTypeTmp == null)
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continue;
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deobfuscate(resolverHandler);
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if (checkHandlerMethod(resolverHandler)) {
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callResolverMethod = attachAppMethod;
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resolverType = resolverTypeTmp;
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return true;
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}
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}
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}
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return false;
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}
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static bool hasLdftn(MethodDef method) {
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if (method == null || method.Body == null)
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return false;
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code == Code.Ldftn)
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return true;
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}
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return false;
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}
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bool checkResolverInitMethod(MethodDef initMethod) {
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resolverType = null;
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if (!initMethod.HasBody)
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return false;
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deobfuscate(initMethod);
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foreach (var handlerDef in getResolverHandlers(initMethod)) {
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deobfuscate(handlerDef);
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var resolverTypeTmp = getResolverType(handlerDef);
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if (resolverTypeTmp == null)
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continue;
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if (checkHandlerMethod(handlerDef)) {
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resolverType = resolverTypeTmp;
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return true;
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}
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}
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return false;
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}
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void deobfuscate(MethodDef method) {
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simpleDeobfuscator.deobfuscate(method);
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simpleDeobfuscator.decryptStrings(method, deob);
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}
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TypeDef getResolverType(MethodDef resolveHandler) {
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if (resolveHandler.Body == null)
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return null;
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foreach (var instr in resolveHandler.Body.Instructions) {
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if (instr.OpCode.Code != Code.Ldsfld && instr.OpCode.Code != Code.Stsfld)
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continue;
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var field = DotNetUtils.getField(module, instr.Operand as IField);
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if (field == null)
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continue;
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if (!checkResolverType(field.DeclaringType))
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continue;
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return field.DeclaringType;
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}
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if (checkResolverType(resolveHandler.DeclaringType))
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return resolveHandler.DeclaringType;
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return null;
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}
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protected abstract bool checkResolverType(TypeDef type);
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protected abstract bool checkHandlerMethod(MethodDef handler);
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IEnumerable<MethodDef> getResolverHandlers(MethodDef method) {
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int numHandlers = 0;
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var instructions = method.Body.Instructions;
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for (int i = 0; i < instructions.Count; i++) {
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var instrs = DotNetUtils.getInstructions(instructions, i, OpCodes.Call, OpCodes.Ldnull, OpCodes.Ldftn, OpCodes.Newobj, OpCodes.Callvirt);
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if (instrs == null)
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continue;
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var call = instrs[0];
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if (!DotNetUtils.isMethod(call.Operand as IMethod, "System.AppDomain", "()"))
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continue;
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var ldftn = instrs[2];
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var handlerDef = DotNetUtils.getMethod(module, ldftn.Operand as IMethod);
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if (handlerDef == null)
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continue;
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var newobj = instrs[3];
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if (!DotNetUtils.isMethod(newobj.Operand as IMethod, "System.Void", "(System.Object,System.IntPtr)"))
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continue;
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var callvirt = instrs[4];
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if (!DotNetUtils.isMethod(callvirt.Operand as IMethod, "System.Void", "(System.ResolveEventHandler)"))
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continue;
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numHandlers++;
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yield return handlerDef;
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}
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// If no handlers found, it's possible that the method itself is the handler.
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if (numHandlers == 0)
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yield return method;
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}
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static bool hasOnlyThisMethod(TypeDef type, MethodDef method) {
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if (type == null || method == null)
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return false;
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foreach (var m in type.Methods) {
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if (m.Name == ".cctor" || m.Name == ".ctor")
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continue;
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if (m == method)
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continue;
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return false;
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}
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return true;
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}
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}
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}
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