2011-11-06 19:19:26 +08:00
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/*
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2012-01-10 06:02:47 +08:00
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Copyright (C) 2011-2012 de4dot@gmail.com
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2011-11-06 19:19:26 +08:00
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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.IO;
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using System.Security.Cryptography;
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using System.Text;
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using Mono.Cecil;
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using de4dot.blocks;
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2011-12-09 16:02:06 +08:00
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namespace de4dot.code.deobfuscators.CliSecure {
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2011-11-06 19:19:26 +08:00
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class ResourceDecrypter {
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ModuleDefinition module;
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TypeDefinition rsrcType;
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MethodDefinition rsrcRrrMethod;
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2012-04-27 02:50:06 +08:00
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MethodDefinition rsrcResolveMethod;
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public bool Detected {
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get { return rsrcType != null; }
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}
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2011-11-06 19:19:26 +08:00
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public TypeDefinition Type {
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get { return rsrcType; }
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}
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public MethodDefinition RsrcRrrMethod {
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get { return rsrcRrrMethod; }
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}
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public ResourceDecrypter(ModuleDefinition module) {
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this.module = module;
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}
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2012-04-27 02:50:06 +08:00
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public ResourceDecrypter(ModuleDefinition module, ResourceDecrypter oldOne) {
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this.module = module;
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rsrcType = lookup(oldOne.rsrcType, "Could not find rsrcType");
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rsrcRrrMethod = lookup(oldOne.rsrcRrrMethod, "Could not find rsrcRrrMethod");
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rsrcResolveMethod = lookup(oldOne.rsrcResolveMethod, "Could not find rsrcResolveMethod");
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}
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T lookup<T>(T def, string errorMessage) where T : MemberReference {
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return DeobUtils.lookup(module, def, errorMessage);
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}
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2011-11-06 19:19:26 +08:00
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public void find() {
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findResourceType();
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}
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2012-04-27 02:50:06 +08:00
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static readonly string[] requiredFields = new string[] {
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"System.Reflection.Assembly",
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"System.String[]",
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};
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2011-11-06 19:19:26 +08:00
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void findResourceType() {
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2012-04-27 02:50:06 +08:00
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var cctor = DotNetUtils.getModuleTypeCctor(module);
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if (cctor == null)
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return;
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foreach (var calledMethod in DotNetUtils.getCalledMethods(module, cctor)) {
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if (!calledMethod.IsStatic || calledMethod.Body == null)
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continue;
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if (!DotNetUtils.isMethod(calledMethod, "System.Void", "()"))
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continue;
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var type = calledMethod.DeclaringType;
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if (!new FieldTypes(type).exactly(requiredFields))
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2011-11-06 19:19:26 +08:00
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continue;
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2012-04-27 02:50:06 +08:00
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var resolveHandler = DotNetUtils.getMethod(type, "System.Reflection.Assembly", "(System.Object,System.ResolveEventArgs)");
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var decryptMethod = DotNetUtils.getMethod(type, "System.Byte[]", "(System.IO.Stream)");
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if (resolveHandler == null || !resolveHandler.IsStatic)
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continue;
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if (decryptMethod == null || !decryptMethod.IsStatic)
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2011-11-06 19:19:26 +08:00
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continue;
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rsrcType = type;
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2012-04-27 02:50:06 +08:00
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rsrcRrrMethod = calledMethod;
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rsrcResolveMethod = resolveHandler;
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2011-11-06 19:19:26 +08:00
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return;
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}
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}
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public EmbeddedResource mergeResources() {
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2012-04-27 02:50:06 +08:00
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if (rsrcResolveMethod == null)
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2011-11-06 19:19:26 +08:00
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return null;
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2012-04-27 02:50:06 +08:00
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var resource = DotNetUtils.getResource(module, DotNetUtils.getCodeStrings(rsrcResolveMethod)) as EmbeddedResource;
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2011-11-06 19:19:26 +08:00
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if (resource == null)
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return null;
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DeobUtils.decryptAndAddResources(module, resource.Name, () => decryptResource(resource));
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return resource;
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}
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byte[] decryptResource(EmbeddedResource resource) {
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using (var rsrcStream = resource.GetResourceStream()) {
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using (var reader = new BinaryReader(rsrcStream)) {
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var key = reader.ReadString();
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var data = reader.ReadBytes((int)(rsrcStream.Length - rsrcStream.Position));
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var cryptoTransform = new DESCryptoServiceProvider {
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Key = Encoding.ASCII.GetBytes(key),
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IV = Encoding.ASCII.GetBytes(key),
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}.CreateDecryptor();
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var memStream = new MemoryStream(data);
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using (var reader2 = new BinaryReader(new CryptoStream(memStream, cryptoTransform, CryptoStreamMode.Read))) {
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return reader2.ReadBytes((int)memStream.Length);
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}
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}
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}
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}
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}
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}
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