Support Rummage

de4dot.code/de4dot.code.csproj

@@ -194,6 +194,8 @@
     <Compile Include="deobfuscators\MethodStack.cs" />
     <Compile Include="deobfuscators\QuickLZ.cs" />
     <Compile Include="deobfuscators\RandomNameChecker.cs" />
+    <Compile Include="deobfuscators\Rummage\Deobfuscator.cs" />
+    <Compile Include="deobfuscators\Rummage\StringDecrypter.cs" />
     <Compile Include="deobfuscators\Skater_NET\Deobfuscator.cs" />
     <Compile Include="deobfuscators\Skater_NET\EnumClassFinder.cs" />
     <Compile Include="deobfuscators\Skater_NET\StringDecrypter.cs" />

de4dot.code/deobfuscators/Rummage/Deobfuscator.cs

@@ -0,0 +1,110 @@
+/*
+    Copyright (C) 2011-2012 de4dot@gmail.com
+
+    This file is part of de4dot.
+
+    de4dot is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    de4dot is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with de4dot.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+using System.Collections.Generic;
+using Mono.Cecil;
+using de4dot.blocks;
+
+namespace de4dot.code.deobfuscators.Rummage {
+	public class DeobfuscatorInfo : DeobfuscatorInfoBase {
+		public const string THE_NAME = "Rummage";
+		public const string THE_TYPE = "rm";
+		const string DEFAULT_REGEX = @"!.";
+		public DeobfuscatorInfo()
+			: base(DEFAULT_REGEX) {
+		}
+
+		public override string Name {
+			get { return THE_NAME; }
+		}
+
+		public override string Type {
+			get { return THE_TYPE; }
+		}
+
+		public override IDeobfuscator createDeobfuscator() {
+			return new Deobfuscator(new Deobfuscator.Options {
+				ValidNameRegex = validNameRegex.get(),
+			});
+		}
+	}
+
+	class Deobfuscator : DeobfuscatorBase {
+		StringDecrypter stringDecrypter;
+
+		internal class Options : OptionsBase {
+		}
+
+		public override string Type {
+			get { return DeobfuscatorInfo.THE_TYPE; }
+		}
+
+		public override string TypeLong {
+			get { return DeobfuscatorInfo.THE_NAME; }
+		}
+
+		public override string Name {
+			get { return TypeLong; }
+		}
+
+		public Deobfuscator(Options options)
+			: base(options) {
+		}
+
+		protected override int detectInternal() {
+			int val = 0;
+
+			int sum = toInt32(stringDecrypter.Detected);
+			if (sum > 0)
+				val += 100 + 10 * (sum - 1);
+
+			return val;
+		}
+
+		protected override void scanForObfuscator() {
+			stringDecrypter = new StringDecrypter(module);
+			stringDecrypter.find();
+		}
+
+		public override void deobfuscateBegin() {
+			base.deobfuscateBegin();
+
+			stringDecrypter.initialize();
+		}
+
+
+		public override void deobfuscateMethodEnd(Blocks blocks) {
+			if (CanRemoveStringDecrypterType)
+				stringDecrypter.deobfuscate(blocks);
+			base.deobfuscateMethodEnd(blocks);
+		}
+
+		public override void deobfuscateEnd() {
+			if (CanRemoveStringDecrypterType) {
+				addTypeToBeRemoved(stringDecrypter.Type, "String decrypter type");
+				addTypesToBeRemoved(stringDecrypter.OtherTypes, "Decrypted string type");
+			}
+			base.deobfuscateEnd();
+		}
+
+		public override IEnumerable<int> getStringDecrypterMethods() {
+			return new List<int>();
+		}
+	}
+}

de4dot.code/deobfuscators/Rummage/StringDecrypter.cs

@@ -0,0 +1,256 @@
+/*
+    Copyright (C) 2011-2012 de4dot@gmail.com
+
+    This file is part of de4dot.
+
+    de4dot is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    de4dot is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with de4dot.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+using Mono.Cecil;
+using Mono.Cecil.Cil;
+using de4dot.blocks;
+
+namespace de4dot.code.deobfuscators.Rummage {
+	class StringDecrypter {
+		ModuleDefinition module;
+		MethodDefinition stringDecrypterMethod;
+		FieldDefinitionAndDeclaringTypeDict<StringInfo> stringInfos = new FieldDefinitionAndDeclaringTypeDict<StringInfo>();
+		int fileDispl;
+		uint[] key;
+		BinaryReader reader;
+
+		class StringInfo {
+			public readonly FieldDefinition field;
+			public readonly int stringId;
+			public string decrypted;
+
+			public StringInfo(FieldDefinition field, int stringId) {
+				this.field = field;
+				this.stringId = stringId;
+			}
+
+			public override string ToString() {
+				if (decrypted != null)
+					return string.Format("{0:X8} - {1}", stringId, Utils.toCsharpString(decrypted));
+				return string.Format("{0:X8}", stringId);
+			}
+		}
+
+		public TypeDefinition Type {
+			get { return stringDecrypterMethod != null ? stringDecrypterMethod.DeclaringType : null; }
+		}
+
+		public IEnumerable<TypeDefinition> OtherTypes {
+			get {
+				var list = new List<TypeDefinition>(stringInfos.Count);
+				foreach (var info in stringInfos.getValues())
+					list.Add(info.field.DeclaringType);
+				return list;
+			}
+		}
+
+		public bool Detected {
+			get { return stringDecrypterMethod != null; }
+		}
+
+		public StringDecrypter(ModuleDefinition module) {
+			this.module = module;
+		}
+
+		public void find() {
+			foreach (var type in module.Types) {
+				var method = checkType(type);
+				if (method == null)
+					continue;
+				if (!getDispl(method, ref fileDispl))
+					continue;
+
+				stringDecrypterMethod = method;
+				break;
+			}
+		}
+
+		static readonly string[] requiredFields = new string[] {
+			"System.UInt32[]",
+		};
+		static readonly string[] requiredLocals = new string[] {
+			"System.Byte[]",
+			"System.Int32",
+			"System.IO.FileStream",
+		};
+		static MethodDefinition checkType(TypeDefinition type) {
+			if (!new FieldTypes(type).exactly(requiredFields))
+				return null;
+			var cctor = DotNetUtils.getMethod(type, ".cctor");
+			if (cctor == null)
+				return null;
+			if (!new LocalTypes(cctor).all(requiredLocals))
+				return null;
+
+			return checkMethods(type);
+		}
+
+		static MethodDefinition checkMethods(TypeDefinition type) {
+			MethodDefinition cctor = null, decrypterMethod = null;
+			foreach (var method in type.Methods) {
+				if (!method.IsStatic || method.Body == null)
+					return null;
+				if (method.Name == ".cctor")
+					cctor = method;
+				else if (DotNetUtils.isMethod(method, "System.String", "(System.Int32)"))
+					decrypterMethod = method;
+				else
+					return null;
+			}
+			if (cctor == null || decrypterMethod == null)
+				return null;
+
+			return decrypterMethod;
+		}
+
+		static bool getDispl(MethodDefinition method, ref int displ) {
+			var instrs = method.Body.Instructions;
+			for (int i = 0; i < instrs.Count - 2; i++) {
+				var mul = instrs[i];
+				if (mul.OpCode.Code != Code.Mul)
+					continue;
+
+				var ldci4 = instrs[i + 1];
+				if (!DotNetUtils.isLdcI4(ldci4))
+					continue;
+
+				var sub = instrs[i + 2];
+				if (sub.OpCode.Code != Code.Sub)
+					continue;
+
+				displ = DotNetUtils.getLdcI4Value(ldci4);
+				return true;
+			}
+
+			return false;
+		}
+
+		public void initialize() {
+			reader = new BinaryReader(new FileStream(module.FullyQualifiedName, FileMode.Open, FileAccess.Read, FileShare.Read));
+			initKey();
+
+			foreach (var type in module.Types)
+				initType(type);
+		}
+
+		void initKey() {
+			reader.BaseStream.Position = reader.BaseStream.Length - 48;
+			key = new uint[4];
+			for (int i = 0; i < key.Length; i++)
+				key[i] = reader.ReadUInt32();
+		}
+
+		void initType(TypeDefinition type) {
+			var cctor = DotNetUtils.getMethod(type, ".cctor");
+			if (cctor == null)
+				return;
+			var info = getStringInfo(cctor);
+			if (info == null)
+				return;
+
+			stringInfos.add(info.field, info);
+		}
+
+		StringInfo getStringInfo(MethodDefinition method) {
+			if (method == null || method.Body == null)
+				return null;
+			var instrs = method.Body.Instructions;
+			for (int i = 0; i < instrs.Count - 2; i++) {
+				var ldci4 = instrs[i];
+				if (!DotNetUtils.isLdcI4(ldci4))
+					continue;
+				int stringId = DotNetUtils.getLdcI4Value(ldci4);
+
+				var call = instrs[i + 1];
+				if (call.OpCode.Code != Code.Call)
+					continue;
+				var calledMethod = call.Operand as MethodReference;
+				if (!MemberReferenceHelper.compareMethodReferenceAndDeclaringType(stringDecrypterMethod, calledMethod))
+					continue;
+
+				var stsfld = instrs[i + 2];
+				if (stsfld.OpCode.Code != Code.Stsfld)
+					continue;
+				var field = stsfld.Operand as FieldDefinition;
+				if (field == null)
+					continue;
+
+				return new StringInfo(field, stringId);
+			}
+
+			return null;
+		}
+
+		public void deobfuscate(Blocks blocks) {
+			foreach (var block in blocks.MethodBlocks.getAllBlocks()) {
+				var instrs = block.Instructions;
+				for (int i = 0; i < instrs.Count; i++) {
+					var instr = instrs[i];
+
+					if (instr.OpCode.Code != Code.Ldsfld)
+						continue;
+
+					var field = instr.Operand as FieldReference;
+					if (field == null)
+						continue;
+					var info = stringInfos.find(field);
+					if (info == null)
+						continue;
+					var decrypted = decrypt(info);
+
+					instrs[i] = new Instr(Instruction.Create(OpCodes.Ldstr, decrypted));
+					Log.v("Decrypted string: {0}", Utils.toCsharpString(decrypted));
+				}
+			}
+		}
+
+		string decrypt(StringInfo info) {
+			if (info.decrypted == null)
+				info.decrypted = decrypt(info.stringId);
+
+			return info.decrypted;
+		}
+
+		string decrypt(int stringId) {
+			reader.BaseStream.Position = reader.BaseStream.Length + (stringId * 4 - fileDispl);
+
+			uint v0 = reader.ReadUInt32();
+			uint v1 = reader.ReadUInt32();
+			DeobUtils.xteaDecrypt(ref v0, ref v1, key, 32);
+			int utf8Length = (int)v0;
+			var decrypted = new uint[(utf8Length + 11) / 8 * 2 - 1];
+			decrypted[0] = v1;
+			for (int i = 1; i + 1 < decrypted.Length; i += 2) {
+				v0 = reader.ReadUInt32();
+				v1 = reader.ReadUInt32();
+				DeobUtils.xteaDecrypt(ref v0, ref v1, key, 32);
+				decrypted[i] = v0;
+				decrypted[i + 1] = v1;
+			}
+
+			var utf8 = new byte[utf8Length];
+			Buffer.BlockCopy(decrypted, 0, utf8, 0, utf8.Length);
+			return Encoding.UTF8.GetString(utf8);
+		}
+	}
+}

de4dot.cui/Program.cs

@@ -48,6 +48,7 @@ namespace de4dot.cui {
 				new de4dot.code.deobfuscators.Eazfuscator_NET.DeobfuscatorInfo(),
 				new de4dot.code.deobfuscators.Goliath_NET.DeobfuscatorInfo(),
 				new de4dot.code.deobfuscators.MaxtoCode.DeobfuscatorInfo(),
+				new de4dot.code.deobfuscators.Rummage.DeobfuscatorInfo(),
 				new de4dot.code.deobfuscators.Skater_NET.DeobfuscatorInfo(),
 				new de4dot.code.deobfuscators.SmartAssembly.DeobfuscatorInfo(),
 				new de4dot.code.deobfuscators.Spices_Net.DeobfuscatorInfo(),