99 lines
2.5 KiB
C#
99 lines
2.5 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.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.CodeFort {
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class StringDecrypter {
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ModuleDefMD module;
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MethodDef decryptMethod;
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public bool Detected {
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get { return decryptMethod != null; }
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}
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public MethodDef Method {
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get { return decryptMethod; }
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}
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public TypeDef Type {
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get { return decryptMethod == null ? null : decryptMethod.DeclaringType; }
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}
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public StringDecrypter(ModuleDefMD module) {
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this.module = module;
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}
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public void Find() {
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foreach (var type in module.Types) {
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var method = CheckType(type);
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if (method == null)
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continue;
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decryptMethod = method;
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}
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}
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static MethodDef CheckType(TypeDef type) {
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if (type.HasFields)
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return null;
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return CheckMethods(type);
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}
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static MethodDef CheckMethods(TypeDef type) {
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MethodDef decryptMethod = null;
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foreach (var method in type.Methods) {
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if (method.Name == ".cctor")
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continue;
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if (!method.IsStatic || method.Body == null)
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return null;
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if (!DotNetUtils.IsMethod(method, "System.String", "(System.String)"))
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return null;
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if (!HasDouble(method, 3992.0))
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return null;
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decryptMethod = method;
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}
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return decryptMethod;
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}
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static bool HasDouble(MethodDef method, double value) {
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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.Ldc_R8)
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continue;
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if ((double)instr.Operand == value)
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return true;
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}
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return false;
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}
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public string Decrypt(string s) {
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var bytes = new byte[s.Length];
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for (int i = 0; i < s.Length; i++)
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bytes[i] = (byte)(s[i] ^ 0x3F);
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return Encoding.UTF8.GetString(bytes);
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}
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}
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}
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