Update tamper code
This commit is contained in:
de4dot
parent
a0f5a109dd
commit
e68cedd44b
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@ -28,6 +28,11 @@ namespace de4dot.deobfuscators.SmartAssembly {
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ModuleDefinition module;
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List<MethodDefinition> pinvokeMethods = new List<MethodDefinition>();
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enum Type {
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V1,
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V2,
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}
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public IList<MethodDefinition> PinvokeMethods {
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get { return pinvokeMethods; }
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}
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@ -61,155 +66,193 @@ namespace de4dot.deobfuscators.SmartAssembly {
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public int End { get; set; }
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}
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IList<BlockInfo> findTamperBlocks(Blocks blocks, IList<Block> allBlocks, out MethodDefinition pinvokeMethod) {
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var list = new List<BlockInfo>(3);
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var first = findFirstBlocks(allBlocks, blocks.Locals, out pinvokeMethod);
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if (first == null)
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return null;
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var second = first[1];
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var badBlock = second.Block.LastInstr.isBrfalse() ? second.Block.Targets[0] : second.Block.FallThrough;
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var last = findLastBlock(badBlock);
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if (last == null)
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return null;
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list.AddRange(first);
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list.Add(last);
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return list;
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class TamperBlocks {
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public Type type;
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public MethodDefinition pinvokeMethod;
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public BlockInfo first;
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public BlockInfo second;
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public BlockInfo bad;
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}
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IList<BlockInfo> findFirstBlocks(IList<Block> allBlocks, IList<VariableDefinition> locals, out MethodDefinition pinvokeMethod) {
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pinvokeMethod = null;
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TamperBlocks findTamperBlocks(Blocks blocks, IList<Block> allBlocks) {
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var tamperBlocks = new TamperBlocks();
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if (!findFirstBlocks(tamperBlocks, allBlocks, blocks.Locals))
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return null;
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var second = tamperBlocks.second;
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var badBlock = second.Block.LastInstr.isBrfalse() ? second.Block.Targets[0] : second.Block.FallThrough;
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tamperBlocks.bad = findBadBlock(badBlock);
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if (tamperBlocks.bad == null)
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return null;
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return tamperBlocks;
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}
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bool findFirstBlocks(TamperBlocks tamperBlocks, IList<Block> allBlocks, IList<VariableDefinition> locals) {
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foreach (var b in allBlocks) {
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if (!b.LastInstr.isBrfalse())
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continue;
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try {
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var block = b;
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var list = new List<BlockInfo>();
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var instrs = block.Instructions;
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int start = instrs.Count - 1;
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int end = start;
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Instr instr;
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MethodReference method;
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/*
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* ldc.i4.0
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* stloc X
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* call GetExecutingAssembly()
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* stloc Y
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* ldloc Y
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* callvirt Location
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* ldc.i4.1
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* ldloca X
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* call StrongNameSignatureVerificationEx
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* pop
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* ldloc X
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* brfalse bad_code
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* ldloc Y
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* callvirt FullName()
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* ldstr "......"
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* callvirt EndsWith(string)
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* brfalse bad_code / brtrue good_code
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*/
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instr = instrs[--start];
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if (!instr.isLdloc())
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continue;
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var loc0 = Instr.getLocalVar(locals, instr);
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instr = instrs[--start];
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if (instr.OpCode != OpCodes.Pop)
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continue;
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instr = instrs[--start];
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if (instr.OpCode != OpCodes.Call)
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continue;
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pinvokeMethod = DotNetUtils.getMethod(module, instr.Operand as MethodReference);
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if (!DotNetUtils.isPinvokeMethod(pinvokeMethod, "mscorwks", "StrongNameSignatureVerificationEx"))
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continue;
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while (true) {
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instr = instrs[--start];
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if (instr.OpCode == OpCodes.Callvirt)
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break;
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}
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method = (MethodReference)instr.Operand;
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if (method.ToString() != "System.String System.Reflection.Assembly::get_Location()")
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continue;
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while (true) {
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instr = instrs[--start];
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if (instr.OpCode == OpCodes.Call)
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break;
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}
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method = (MethodReference)instr.Operand;
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if (method.ToString() != "System.Reflection.Assembly System.Reflection.Assembly::GetExecutingAssembly()")
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continue;
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instr = instrs[--start];
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if (!instr.isStloc() || Instr.getLocalVar(locals, instr) != loc0)
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continue;
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instr = instrs[--start];
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if (!instr.isLdcI4())
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continue;
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list.Add(new BlockInfo {
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Block = block,
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Start = start,
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End = end,
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});
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block = block.FallThrough;
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instrs = block.Instructions;
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start = end = 0;
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instr = instrs[end++];
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if (!instr.isLdloc())
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continue;
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instr = instrs[end++];
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if (instr.OpCode != OpCodes.Callvirt)
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continue;
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method = (MethodReference)instr.Operand;
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if (method.ToString() != "System.String System.Reflection.Assembly::get_FullName()")
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continue;
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instr = instrs[end++];
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if (instr.OpCode != OpCodes.Ldstr)
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continue;
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instr = instrs[end++];
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if (instr.OpCode != OpCodes.Callvirt)
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continue;
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method = (MethodReference)instr.Operand;
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if (method.ToString() != "System.Boolean System.String::EndsWith(System.String)")
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continue;
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instr = instrs[end++];
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if (!instr.isBrfalse() && !instr.isBrtrue())
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continue;
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end--;
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list.Add(new BlockInfo {
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Block = block,
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Start = start,
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End = end,
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});
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return list;
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if (findFirstBlocks(b, tamperBlocks, allBlocks, locals))
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return true;
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}
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catch (ArgumentOutOfRangeException) {
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continue;
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}
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}
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return null;
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return false;
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}
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BlockInfo findLastBlock(Block last) {
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static int findCallMethod(Block block, int index, bool keepLooking, Func<MethodReference, bool> func) {
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var instrs = block.Instructions;
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for (int i = index; i < instrs.Count; i++) {
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var instr = instrs[i];
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if (instr.OpCode.Code != Code.Call && instr.OpCode.Code != Code.Callvirt)
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continue;
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var calledMethod = instr.Operand as MethodReference;
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if (calledMethod != null && func(calledMethod))
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return i;
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if (!keepLooking)
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return -1;
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}
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return -1;
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}
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bool findFirstBlocks(Block block, TamperBlocks tamperBlocks, IList<Block> allBlocks, IList<VariableDefinition> locals) {
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if (!block.LastInstr.isBrfalse())
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return false;
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/*
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* ldc.i4.0
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* stloc X
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* call GetExecutingAssembly()
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* stloc Y
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* ldloc Y
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* callvirt Location
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* ldc.i4.1
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* ldloca X
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* call StrongNameSignatureVerificationEx
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* pop / brfalse bad_code
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* ldloc X
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* brfalse bad_code
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* ldloc Y
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* callvirt FullName()
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* ldstr "......"
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* callvirt EndsWith(string)
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* brfalse bad_code / brtrue good_code
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*/
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var instrs = block.Instructions;
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int end = instrs.Count - 1;
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Instr instr;
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MethodReference method;
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tamperBlocks.type = Type.V1;
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int index = 0;
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int start = findCallMethod(block, index, true, (calledMethod) => calledMethod.ToString() == "System.Reflection.Assembly System.Reflection.Assembly::GetExecutingAssembly()");
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if (start < 0)
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return false;
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index = start + 1;
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instr = instrs[--start];
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if (!instr.isStloc())
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return false;
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var loc0 = Instr.getLocalVar(locals, instr);
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instr = instrs[--start];
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if (!instr.isLdcI4())
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return false;
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index = findCallMethod(block, index, false, (calledMethod) => calledMethod.ToString() == "System.String System.Reflection.Assembly::get_Location()");
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if (index < 0)
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return false;
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index++;
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index = findCallMethod(block, index, false, (calledMethod) => {
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tamperBlocks.pinvokeMethod = DotNetUtils.getMethod(module, calledMethod);
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return DotNetUtils.isPinvokeMethod(tamperBlocks.pinvokeMethod, "mscorwks", "StrongNameSignatureVerificationEx");
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});
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if (index < 0)
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return false;
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index++;
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if (!instrs[index].isBrfalse()) {
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if (instrs[index].OpCode.Code != Code.Pop)
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return false;
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instr = instrs[index + 1];
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if (!instr.isLdloc() || Instr.getLocalVar(locals, instr) != loc0)
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return false;
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if (!instrs[index + 2].isBrfalse())
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return false;
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tamperBlocks.type = Type.V1;
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tamperBlocks.first = new BlockInfo {
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Block = block,
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Start = start,
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End = end,
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};
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}
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else {
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tamperBlocks.type = Type.V2;
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tamperBlocks.first = new BlockInfo {
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Block = block,
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Start = start,
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End = end,
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};
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block = block.FallThrough;
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if (block == null)
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return false;
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instrs = block.Instructions;
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index = 0;
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instr = instrs[index];
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if (!instr.isLdloc() || Instr.getLocalVar(locals, instr) != loc0)
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return false;
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if (!instrs[index + 1].isBrfalse())
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return false;
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}
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block = block.FallThrough;
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instrs = block.Instructions;
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start = end = 0;
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instr = instrs[end++];
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if (!instr.isLdloc())
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return false;
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instr = instrs[end++];
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if (instr.OpCode != OpCodes.Callvirt)
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return false;
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method = (MethodReference)instr.Operand;
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if (method.ToString() != "System.String System.Reflection.Assembly::get_FullName()")
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return false;
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instr = instrs[end++];
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if (instr.OpCode != OpCodes.Ldstr)
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return false;
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instr = instrs[end++];
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if (instr.OpCode != OpCodes.Callvirt)
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return false;
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method = (MethodReference)instr.Operand;
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if (method.ToString() != "System.Boolean System.String::EndsWith(System.String)")
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return false;
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instr = instrs[end++];
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if (!instr.isBrfalse() && !instr.isBrtrue())
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return false;
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end--;
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tamperBlocks.second = new BlockInfo {
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Block = block,
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Start = start,
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End = end,
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};
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return true;
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}
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BlockInfo findBadBlock(Block last) {
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/*
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* ldstr "........."
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* newobj System.Security.SecurityException(string)
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@ -248,42 +291,66 @@ namespace de4dot.deobfuscators.SmartAssembly {
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}
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bool removeTamperProtection(Blocks blocks) {
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MethodDefinition pinvokeMethod;
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var allBlocks = new List<Block>(blocks.MethodBlocks.getAllBlocks());
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var blockInfos = findTamperBlocks(blocks, allBlocks, out pinvokeMethod);
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var tamperBlocks = findTamperBlocks(blocks, allBlocks);
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if (blockInfos == null) {
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if (tamperBlocks == null) {
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if (isTamperProtected(allBlocks))
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Log.w("Could not remove tamper protection code: {0} ({1:X8})", blocks.Method, blocks.Method.MetadataToken.ToUInt32());
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return false;
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}
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if (blockInfos.Count != 3)
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throw new ApplicationException("Invalid state");
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var first = blockInfos[0];
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var second = blockInfos[1];
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var bad = blockInfos[2];
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if (first.Block.Targets.Count != 1 || first.Block.Targets[0] != bad.Block)
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throw new ApplicationException("Invalid state");
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if (second.Start != 0 || second.End + 1 != second.Block.Instructions.Count)
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throw new ApplicationException("Invalid state");
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if (bad.Start != 0 || bad.End + 1 != bad.Block.Instructions.Count)
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throw new ApplicationException("Invalid state");
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var goodBlock = second.Block.LastInstr.isBrtrue() ? second.Block.Targets[0] : second.Block.FallThrough;
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first.Block.remove(first.Start, first.End - first.Start + 1);
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first.Block.replaceLastInstrsWithBranch(0, goodBlock);
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removeDeadBlock(second);
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removeDeadBlock(bad);
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pinvokeMethods.Add(pinvokeMethod);
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switch (tamperBlocks.type) {
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case Type.V1:
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removeTamperV1(tamperBlocks);
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break;
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case Type.V2:
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removeTamperV2(tamperBlocks);
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break;
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default:
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throw new ApplicationException("Unknown type");
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}
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pinvokeMethods.Add(tamperBlocks.pinvokeMethod);
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return true;
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}
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void removeDeadBlock(BlockInfo info) {
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var parent = (ScopeBlock)info.Block.Parent;
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void removeTamperV1(TamperBlocks tamperBlocks) {
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var first = tamperBlocks.first;
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var second = tamperBlocks.second;
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var bad = tamperBlocks.bad;
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var goodBlock = second.Block.LastInstr.isBrtrue() ? second.Block.Targets[0] : second.Block.FallThrough;
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if (first.Block.Targets.Count != 1 || first.Block.Targets[0] != bad.Block)
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throw new ApplicationException("Invalid state");
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first.Block.remove(first.Start, first.End - first.Start + 1);
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first.Block.replaceLastInstrsWithBranch(0, goodBlock);
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removeDeadBlock(second.Block);
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removeDeadBlock(bad.Block);
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}
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void removeTamperV2(TamperBlocks tamperBlocks) {
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var first = tamperBlocks.first;
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var second = tamperBlocks.second.Block;
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var bad = tamperBlocks.bad.Block;
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var firstFallthrough = first.Block.FallThrough;
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var goodBlock = second.LastInstr.isBrtrue() ? second.Targets[0] : second.FallThrough;
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if (first.Block.Targets.Count != 1 || first.Block.Targets[0] != bad)
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throw new ApplicationException("Invalid state");
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first.Block.remove(first.Start, first.End - first.Start + 1);
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first.Block.replaceLastInstrsWithBranch(0, goodBlock);
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removeDeadBlock(firstFallthrough);
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removeDeadBlock(second);
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removeDeadBlock(bad);
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}
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void removeDeadBlock(Block block) {
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var parent = (ScopeBlock)block.Parent;
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if (parent != null) // null if already dead
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parent.removeDeadBlock(info.Block);
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parent.removeDeadBlock(block);
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}
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}
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}
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