336 lines
11 KiB
C#
336 lines
11 KiB
C#
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/*
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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;
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using System.Collections.Generic;
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using System.IO;
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using System.Text;
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using Mono.Cecil;
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using Mono.Cecil.Cil;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators.Confuser {
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class ProxyCallFixerV1 : ProxyCallFixer2 {
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MethodDefinitionAndDeclaringTypeDict<ProxyCreatorInfo> methodToInfo = new MethodDefinitionAndDeclaringTypeDict<ProxyCreatorInfo>();
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FieldDefinitionAndDeclaringTypeDict<MethodDefinition> fieldToMethod = new FieldDefinitionAndDeclaringTypeDict<MethodDefinition>();
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string ourAsm;
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enum ProxyCreatorType {
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None,
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CallOrCallvirt,
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Newobj,
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}
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class ProxyCreatorInfo {
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public readonly MethodDefinition creatorMethod;
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public readonly ProxyCreatorType proxyCreatorType;
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public ProxyCreatorInfo(MethodDefinition creatorMethod, ProxyCreatorType proxyCreatorType) {
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this.creatorMethod = creatorMethod;
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this.proxyCreatorType = proxyCreatorType;
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}
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}
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class DelegateInitInfo {
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public readonly byte[] data;
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public readonly FieldDefinition field;
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public readonly MethodDefinition creatorMethod;
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public DelegateInitInfo(string data, FieldDefinition field, MethodDefinition creatorMethod) {
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this.data = Convert.FromBase64String(data);
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this.field = field;
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this.creatorMethod = creatorMethod;
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}
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}
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protected override bool ProxyCallIsObfuscated {
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get { return true; }
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}
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public IEnumerable<FieldDefinition> Fields {
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get { return fieldToMethod.getKeys(); }
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}
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public override IEnumerable<Tuple<MethodDefinition, string>> OtherMethods {
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get {
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var list = new List<Tuple<MethodDefinition, string>>();
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foreach (var creatorMethod in methodToInfo.getKeys()) {
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list.Add(new Tuple<MethodDefinition, string> {
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Item1 = creatorMethod,
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Item2 = "Delegate creator method",
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});
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}
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foreach (var method in fieldToMethod.getValues()) {
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list.Add(new Tuple<MethodDefinition, string> {
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Item1 = method,
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Item2 = "Proxy delegate method",
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});
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}
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return list;
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}
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}
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public ProxyCallFixerV1(ModuleDefinition module)
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: base(module) {
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ourAsm = (module.Assembly.Name ?? new AssemblyNameReference(" -1-1-1-1-1- ", new Version(1, 2, 3, 4))).FullName;
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}
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protected override object checkCctor(TypeDefinition type, MethodDefinition cctor) {
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throw new NotSupportedException();
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}
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protected override void getCallInfo(object context, FieldDefinition field, out MethodReference calledMethod, out OpCode callOpcode) {
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var info = (DelegateInitInfo)context;
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var creatorInfo = methodToInfo.find(info.creatorMethod);
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var reader = new BinaryReader(new MemoryStream(info.data));
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bool isCallvirt = false;
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if (creatorInfo.proxyCreatorType == ProxyCreatorType.CallOrCallvirt)
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isCallvirt = reader.ReadBoolean();
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var asmRef = readAssemblyNameReference(reader);
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uint token = reader.ReadUInt32();
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if (reader.BaseStream.Position != reader.BaseStream.Length)
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throw new ApplicationException("Extra data");
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if (asmRef.FullName == ourAsm)
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calledMethod = (MethodReference)module.LookupToken((int)token);
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else
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calledMethod = createMethodReference(asmRef, token);
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callOpcode = getCallOpCode(creatorInfo, isCallvirt);
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}
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// A method token is not a stable value so this method can fail to return the correct method!
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// There's nothing I can do about that. It's an obfuscator bug.
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MethodReference createMethodReference(AssemblyNameReference asmRef, uint methodToken) {
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var asm = AssemblyResolver.Instance.Resolve(asmRef);
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if (asm == null)
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return null;
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var method = asm.MainModule.LookupToken((int)methodToken) as MethodDefinition;
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if (method == null)
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return null;
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return module.Import(method);
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}
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static AssemblyNameReference readAssemblyNameReference(BinaryReader reader) {
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var name = readString(reader);
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var version = new Version(reader.ReadInt16(), reader.ReadInt16(), reader.ReadInt16(), reader.ReadInt16());
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var culture = readString(reader);
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byte[] pkt = reader.ReadBoolean() ? reader.ReadBytes(8) : null;
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return new AssemblyNameReference(name, version) {
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Culture = culture,
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PublicKeyToken = pkt,
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};
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}
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static string readString(BinaryReader reader) {
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int len = reader.ReadByte();
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var bytes = new byte[len];
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for (int i = 0; i < len; i++)
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bytes[i] = (byte)(reader.ReadByte() ^ len);
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return Encoding.UTF8.GetString(bytes);
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}
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static OpCode getCallOpCode(ProxyCreatorInfo info, bool isCallvirt) {
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switch (info.proxyCreatorType) {
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case ProxyCreatorType.Newobj:
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return OpCodes.Newobj;
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case ProxyCreatorType.CallOrCallvirt:
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return isCallvirt ? OpCodes.Callvirt : OpCodes.Call;
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default: throw new NotImplementedException();
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}
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}
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public void findDelegateCreator() {
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var type = DotNetUtils.getModuleType(module);
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foreach (var method in type.Methods) {
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if (method.Body == null || !method.IsStatic || !method.IsAssembly)
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continue;
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if (!DotNetUtils.isMethod(method, "System.Void", "(System.String,System.RuntimeFieldHandle)"))
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continue;
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var proxyType = getProxyCreatorType(method);
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if (proxyType == ProxyCreatorType.None)
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continue;
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setDelegateCreatorMethod(method);
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methodToInfo.add(method, new ProxyCreatorInfo(method, proxyType));
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}
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}
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static ProxyCreatorType getProxyCreatorType(MethodDefinition method) {
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foreach (var instr in method.Body.Instructions) {
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var field = instr.Operand as FieldReference;
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if (field == null)
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continue;
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switch (field.FullName) {
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case "System.Reflection.Emit.OpCode System.Reflection.Emit.OpCodes::Call":
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case "System.Reflection.Emit.OpCode System.Reflection.Emit.OpCodes::Callvirt":
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return ProxyCreatorType.CallOrCallvirt;
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case "System.Reflection.Emit.OpCode System.Reflection.Emit.OpCodes::Newobj":
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return ProxyCreatorType.Newobj;
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}
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}
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return ProxyCreatorType.None;
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}
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public new void find() {
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if (delegateCreatorMethods.Count == 0)
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return;
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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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Log.v("Finding all proxy delegates");
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var delegateInfos = createDelegateInitInfos(cctor);
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fieldToMethod = createFieldToMethodDictionary(cctor.DeclaringType);
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if (delegateInfos.Count != fieldToMethod.Count)
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throw new ApplicationException("Missing proxy delegates");
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var delegateToFields = new Dictionary<TypeDefinition, List<FieldDefinition>>();
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foreach (var field in fieldToMethod.getKeys()) {
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List<FieldDefinition> list;
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if (!delegateToFields.TryGetValue((TypeDefinition)field.FieldType, out list))
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delegateToFields[(TypeDefinition)field.FieldType] = list = new List<FieldDefinition>();
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list.Add(field);
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}
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foreach (var kv in delegateToFields) {
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var type = kv.Key;
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var fields = kv.Value;
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Log.v("Found proxy delegate: {0} ({1:X8})", Utils.removeNewlines(type), type.MetadataToken.ToInt32());
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RemovedDelegateCreatorCalls++;
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Log.indent();
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foreach (var field in fields) {
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var proxyMethod = fieldToMethod.find(field);
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if (proxyMethod == null)
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continue;
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var info = delegateInfos.find(field);
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if (info == null)
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throw new ApplicationException("Missing proxy info");
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MethodReference calledMethod;
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OpCode callOpcode;
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getCallInfo(info, field, out calledMethod, out callOpcode);
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if (calledMethod == null)
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continue;
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add(proxyMethod, new DelegateInfo(field, calledMethod, callOpcode));
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Log.v("Field: {0}, Opcode: {1}, Method: {2} ({3:X8})",
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Utils.removeNewlines(field.Name),
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callOpcode,
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Utils.removeNewlines(calledMethod),
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calledMethod.MetadataToken.ToUInt32());
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}
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Log.deIndent();
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delegateTypesDict[type] = true;
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}
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}
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FieldDefinitionAndDeclaringTypeDict<DelegateInitInfo> createDelegateInitInfos(MethodDefinition method) {
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var infos = new FieldDefinitionAndDeclaringTypeDict<DelegateInitInfo>();
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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 ldstr = instrs[i];
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if (ldstr.OpCode.Code != Code.Ldstr)
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continue;
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var info = ldstr.Operand as string;
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if (info == null)
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continue;
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var ldtoken = instrs[i + 1];
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if (ldtoken.OpCode.Code != Code.Ldtoken)
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continue;
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var delegateField = ldtoken.Operand as FieldDefinition;
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if (delegateField == null)
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continue;
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var delegateType = delegateField.FieldType as TypeDefinition;
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if (!DotNetUtils.derivesFromDelegate(delegateType))
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continue;
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var call = instrs[i + 2];
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if (call.OpCode.Code != Code.Call)
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continue;
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var delegateCreatorMethod = call.Operand as MethodDefinition;
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if (delegateCreatorMethod == null || !isDelegateCreatorMethod(delegateCreatorMethod))
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continue;
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infos.add(delegateField, new DelegateInitInfo(info, delegateField, delegateCreatorMethod));
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i += 2;
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}
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return infos;
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}
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static FieldDefinitionAndDeclaringTypeDict<MethodDefinition> createFieldToMethodDictionary(TypeDefinition type) {
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var dict = new FieldDefinitionAndDeclaringTypeDict<MethodDefinition>();
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foreach (var method in type.Methods) {
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if (!method.IsStatic || method.Body == null || method.Name == ".cctor")
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continue;
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var delegateField = getDelegateField(method);
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if (delegateField == null)
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continue;
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dict.add(delegateField, method);
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}
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return dict;
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}
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static FieldDefinition getDelegateField(MethodDefinition method) {
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if (method == null || method.Body == null)
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return null;
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FieldDefinition field = null;
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bool foundInvoke = false;
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foreach (var instr in method.Body.Instructions) {
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if (instr.OpCode.Code == Code.Ldsfld) {
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var field2 = instr.Operand as FieldDefinition;
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if (field2 == null || field2.DeclaringType != method.DeclaringType)
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continue;
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if (field != null)
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return null;
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if (!DotNetUtils.derivesFromDelegate(field2.FieldType as TypeDefinition))
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continue;
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field = field2;
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}
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else if (instr.OpCode.Code == Code.Call || instr.OpCode.Code == Code.Callvirt) {
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var calledMethod = instr.Operand as MethodReference;
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foundInvoke |= calledMethod != null && calledMethod.Name == "Invoke";
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}
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}
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return foundInvoke ? field : null;
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}
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public void cleanUp() {
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if (!Detected)
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return;
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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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cctor.Body.Instructions.Clear();
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cctor.Body.Instructions.Add(Instruction.Create(OpCodes.Ret));
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}
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}
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}
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