134 lines
4.1 KiB
C#
134 lines
4.1 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 System.Text;
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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.Babel_NET {
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static class BabelUtils {
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public static EmbeddedResource findEmbeddedResource(ModuleDefMD module, TypeDef decrypterType) {
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return findEmbeddedResource(module, decrypterType, (method) => { });
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}
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public static EmbeddedResource findEmbeddedResource(ModuleDefMD module, TypeDef decrypterType, ISimpleDeobfuscator simpleDeobfuscator, IDeobfuscator deob) {
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return findEmbeddedResource(module, decrypterType, (method) => {
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simpleDeobfuscator.deobfuscate(method);
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simpleDeobfuscator.decryptStrings(method, deob);
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});
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}
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public static EmbeddedResource findEmbeddedResource(ModuleDefMD module, TypeDef decrypterType, Action<MethodDef> fixMethod) {
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foreach (var method in decrypterType.Methods) {
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if (!DotNetUtils.isMethod(method, "System.String", "()"))
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continue;
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if (!method.IsStatic)
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continue;
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fixMethod(method);
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var resource = findEmbeddedResource1(module, method) ?? findEmbeddedResource2(module, method);
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if (resource != null)
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return resource;
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}
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return null;
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}
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static EmbeddedResource findEmbeddedResource1(ModuleDefMD module, MethodDef method) {
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foreach (var s in DotNetUtils.getCodeStrings(method)) {
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var resource = DotNetUtils.getResource(module, s) as EmbeddedResource;
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if (resource != null)
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return resource;
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}
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return null;
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}
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static EmbeddedResource findEmbeddedResource2(ModuleDefMD module, MethodDef method) {
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var strings = new List<string>(DotNetUtils.getCodeStrings(method));
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if (strings.Count != 1)
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return null;
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var encryptedString = strings[0];
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int xorKey;
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if (!getXorKey2(method, out xorKey))
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return null;
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var sb = new StringBuilder(encryptedString.Length);
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foreach (var c in encryptedString)
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sb.Append((char)(c ^ xorKey));
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return DotNetUtils.getResource(module, sb.ToString()) as EmbeddedResource;
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}
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static bool getXorKey2(MethodDef method, out int xorKey) {
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var instrs = method.Body.Instructions;
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for (int i = 0; i < instrs.Count - 2; i++) {
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var ldelem = instrs[i];
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if (ldelem.OpCode.Code != Code.Ldelem_U2)
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continue;
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var ldci4 = instrs[i + 1];
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if (!ldci4.IsLdcI4())
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continue;
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if (instrs[i + 2].OpCode.Code != Code.Xor)
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continue;
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xorKey = ldci4.GetLdcI4Value();
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return true;
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}
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xorKey = 0;
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return false;
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}
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public static bool findRegisterMethod(TypeDef type, out MethodDef regMethod, out MethodDef handler) {
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foreach (var method in type.Methods) {
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if (!method.IsStatic || method.Body == null)
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continue;
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if (method.Body.ExceptionHandlers.Count != 1)
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continue;
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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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continue;
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var handlerRef = instr.Operand as IMethod;
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if (handlerRef == null)
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continue;
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if (!DotNetUtils.isMethod(handlerRef, "System.Reflection.Assembly", "(System.Object,System.ResolveEventArgs)"))
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continue;
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if (!new SigComparer().Equals(type, handlerRef.DeclaringType))
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continue;
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handler = DotNetUtils.getMethod(type, handlerRef);
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if (handler == null)
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continue;
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if (handler.Body == null || handler.Body.ExceptionHandlers.Count != 1)
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continue;
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regMethod = method;
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return true;
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}
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}
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regMethod = null;
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handler = null;
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return false;
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}
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}
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}
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