117 lines
3.4 KiB
C#
117 lines
3.4 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.Text;
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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.Goliath_NET {
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class StringDecrypter : DecrypterBase {
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IType delegateReturnType;
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FieldDef stringStructField;
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public TypeDef StringStruct {
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get { return Detected && stringStructField != null ? stringStructField.DeclaringType : null; }
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}
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public StringDecrypter(ModuleDefMD module)
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: base(module) {
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}
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/*static string[] requiredFields = new string[] {
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"System.Byte[]",
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"System.Collections.Generic.Dictionary`2<System.Int32,System.String>",
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};*/
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protected override bool CheckDecrypterType(TypeDef type) {
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var fields = type.Fields;
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if (fields.Count != 2)
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return false;
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if (fields[0].FieldType.FullName != "System.Byte[]")
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return false;
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var dict = fields[1].FieldType.ToGenericInstSig();
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if (dict == null || dict.GenericArguments.Count != 2)
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return false;
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if (dict.GenericType.GetFullName() != "System.Collections.Generic.Dictionary`2")
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return false;
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if (dict.GenericArguments[0].FullName != "System.Int32")
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return false;
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var garg = dict.GenericArguments[1];
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if (garg.FullName != "System.String") {
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if (!garg.IsValueType)
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return false;
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var gargType = DotNetUtils.GetType(module, garg);
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if (gargType == null || !gargType.IsClass)
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return false;
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if (gargType.Fields.Count != 1)
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return false;
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var field = gargType.Fields[0];
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if (field.FieldType.FullName != "System.String")
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return false;
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delegateReturnType = gargType;
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stringStructField = field;
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}
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else {
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delegateReturnType = garg;
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stringStructField = null;
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}
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return true;
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}
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protected override bool CheckDelegateInvokeMethod(MethodDef invokeMethod) {
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return DotNetUtils.IsMethod(invokeMethod, delegateReturnType.FullName, "(System.Int32)");
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}
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public string Decrypt(MethodDef method) {
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var info = GetInfo(method);
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decryptedReader.BaseStream.Position = info.offset;
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int len = decryptedReader.ReadInt32();
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return Encoding.UTF8.GetString(decryptedReader.ReadBytes(len));
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}
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public void Deobfuscate(Blocks blocks) {
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if (!Detected)
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return;
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if (stringStructField == null)
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return;
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foreach (var block in blocks.MethodBlocks.GetAllBlocks()) {
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count - 1; i++) {
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var ldstr = instrs[i];
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if (ldstr.OpCode.Code != Code.Ldstr)
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continue;
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var ldfld = instrs[i + 1];
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if (ldfld.OpCode.Code != Code.Ldfld)
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continue;
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if (!FieldEqualityComparer.CompareDeclaringTypes.Equals(stringStructField, ldfld.Operand as IField))
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continue;
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block.Remove(i + 1, 1);
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}
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}
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}
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}
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}
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