diff --git a/de4dot.code/deobfuscators/Babel_NET/Deobfuscator.cs b/de4dot.code/deobfuscators/Babel_NET/Deobfuscator.cs
index d63580ed..550fd488 100644
--- a/de4dot.code/deobfuscators/Babel_NET/Deobfuscator.cs
+++ b/de4dot.code/deobfuscators/Babel_NET/Deobfuscator.cs
@@ -175,7 +175,7 @@ namespace de4dot.code.deobfuscators.Babel_NET {
if (stringDecrypter.Resource != null) {
Log.v("Adding string decrypter. Resource: {0}", Utils.toCsharpString(stringDecrypter.Resource.Name));
staticStringDecrypter.add(stringDecrypter.DecryptMethod, (method, args) => {
- return stringDecrypter.decrypt((int)args[0]);
+ return stringDecrypter.decrypt(args);
});
DeobfuscatedFile.stringDecryptersAdded();
}
diff --git a/de4dot.code/deobfuscators/Babel_NET/ResourceDecrypter.cs b/de4dot.code/deobfuscators/Babel_NET/ResourceDecrypter.cs
index 13623ccc..2294482b 100644
--- a/de4dot.code/deobfuscators/Babel_NET/ResourceDecrypter.cs
+++ b/de4dot.code/deobfuscators/Babel_NET/ResourceDecrypter.cs
@@ -30,13 +30,51 @@ namespace de4dot.code.deobfuscators.Babel_NET {
}
public byte[] decrypt(byte[] encryptedData) {
+ if (isV30(encryptedData))
+ return decryptV30(encryptedData);
+ return decryptV35(encryptedData);
+ }
+
+ static bool isV30(byte[] data) {
+ return data.Length > 10 && data[0] == 8 && data[9] <= 1 && data[10] == 8;
+ }
+
+ // v3.0
+ byte[] decryptV30(byte[] encryptedData) {
+ byte[] key, iv;
+ var reader = new BinaryReader(new MemoryStream(encryptedData));
+ bool isCompressed = getHeaderData30(reader, out key, out iv);
+ var data = DeobUtils.desDecrypt(encryptedData,
+ (int)reader.BaseStream.Position,
+ (int)(reader.BaseStream.Length - reader.BaseStream.Position),
+ key, iv);
+ if (isCompressed)
+ data = DeobUtils.inflate(data, true);
+ return data;
+ }
+
+ bool getHeaderData30(BinaryReader reader, out byte[] key, out byte[] iv) {
+ iv = reader.ReadBytes(reader.ReadByte());
+ bool hasEmbeddedKey = reader.ReadBoolean();
+ if (hasEmbeddedKey)
+ key = reader.ReadBytes(reader.ReadByte());
+ else {
+ key = new byte[reader.ReadByte()];
+ Array.Copy(module.Assembly.Name.PublicKey, 0, key, 0, key.Length);
+ }
+
+ reader.ReadBytes(reader.ReadInt32()); // hash
+ return true;
+ }
+
+ // v3.5+
+ byte[] decryptV35(byte[] encryptedData) {
int index = 0;
byte[] key, iv;
bool isCompressed = getKeyIv(getHeaderData(encryptedData, ref index), out key, out iv);
var data = DeobUtils.desDecrypt(encryptedData, index, encryptedData.Length - index, key, iv);
if (isCompressed)
data = DeobUtils.inflate(data, true);
-
return data;
}
@@ -59,7 +97,7 @@ namespace de4dot.code.deobfuscators.Babel_NET {
bool getKeyIv(byte[] headerData, out byte[] key, out byte[] iv) {
var reader = new BinaryReader(new MemoryStream(headerData));
- // 3.5 doesn't have this field
+ // 3.0 - 3.5 don't have this field
if (headerData[(int)reader.BaseStream.Position] != 8) {
var license = reader.ReadString();
}
diff --git a/de4dot.code/deobfuscators/Babel_NET/StringDecrypter.cs b/de4dot.code/deobfuscators/Babel_NET/StringDecrypter.cs
index bc0ef1fe..4aed6c71 100644
--- a/de4dot.code/deobfuscators/Babel_NET/StringDecrypter.cs
+++ b/de4dot.code/deobfuscators/Babel_NET/StringDecrypter.cs
@@ -17,18 +17,77 @@
along with de4dot. If not, see .
*/
+using System;
using System.Collections.Generic;
using System.IO;
+using System.Text;
using Mono.Cecil;
using de4dot.blocks;
namespace de4dot.code.deobfuscators.Babel_NET {
class StringDecrypter {
ModuleDefinition module;
- Dictionary offsetToString = new Dictionary();
TypeDefinition decrypterType;
- MethodDefinition decryptMethod;
EmbeddedResource encryptedResource;
+ IDecrypterInfo decrypterInfo;
+
+ interface IDecrypterInfo {
+ MethodDefinition Decrypter { get; }
+ bool NeedsResource { get; }
+ void initialize(ModuleDefinition module, EmbeddedResource resource);
+ string decrypt(object[] args);
+ }
+
+ class DecrypterInfoV1 : IDecrypterInfo {
+ byte[] key;
+
+ public MethodDefinition Decrypter { get; set; }
+ public bool NeedsResource {
+ get { return true; }
+ }
+
+ public void initialize(ModuleDefinition module, EmbeddedResource resource) {
+ key = resource.GetResourceData();
+ if (key.Length != 0x100)
+ throw new ApplicationException(string.Format("Unknown key length: {0}", key.Length));
+ }
+
+ public string decrypt(object[] args) {
+ return decrypt((string)args[0], (int)args[1]);
+ }
+
+ string decrypt(string s, int k) {
+ var sb = new StringBuilder(s.Length);
+ byte b = key[(byte)k];
+ foreach (var c in s)
+ sb.Append((char)(c ^ (b | k)));
+ return sb.ToString();
+ }
+ }
+
+ class DecrypterInfoV2 : IDecrypterInfo {
+ Dictionary offsetToString = new Dictionary();
+
+ public MethodDefinition Decrypter { get; set; }
+ public bool NeedsResource {
+ get { return true; }
+ }
+
+ public void initialize(ModuleDefinition module, EmbeddedResource resource) {
+ var decrypted = new ResourceDecrypter(module).decrypt(resource.GetResourceData());
+ var reader = new BinaryReader(new MemoryStream(decrypted));
+ while (reader.BaseStream.Position < reader.BaseStream.Length)
+ offsetToString[(int)reader.BaseStream.Position] = reader.ReadString();
+ }
+
+ public string decrypt(object[] args) {
+ return decrypt((int)args[0]);
+ }
+
+ string decrypt(int offset) {
+ return offsetToString[offset];
+ }
+ }
public bool Detected {
get { return decrypterType != null; }
@@ -39,7 +98,7 @@ namespace de4dot.code.deobfuscators.Babel_NET {
}
public MethodDefinition DecryptMethod {
- get { return decryptMethod; }
+ get { return decrypterInfo == null ? null : decrypterInfo.Decrypter; }
}
public EmbeddedResource Resource {
@@ -52,58 +111,98 @@ namespace de4dot.code.deobfuscators.Babel_NET {
public void find() {
foreach (var type in module.Types) {
- if (!isDecrypterType(type))
- continue;
-
- var method = DotNetUtils.getMethod(type, "System.String", "(System.Int32)");
- if (method == null)
+ var info = checkDecrypterType(type);
+ if (info == null)
continue;
decrypterType = type;
- decryptMethod = method;
+ decrypterInfo = info;
return;
}
}
- bool isDecrypterType(TypeDefinition type) {
+ IDecrypterInfo checkDecrypterType(TypeDefinition type) {
if (type.HasEvents)
- return false;
- if (type.NestedTypes.Count != 1)
- return false;
- if (type.Fields.Count != 0)
- return false;
+ return null;
+ if (type.NestedTypes.Count > 2)
+ return null;
+ if (type.Fields.Count > 1)
+ return null;
- var nested = type.NestedTypes[0];
+ foreach (var nested in type.NestedTypes) {
+ var info = checkNested(type, nested);
+ if (info != null)
+ return info;
+ }
+ return null;
+ }
+
+ IDecrypterInfo checkNested(TypeDefinition type, TypeDefinition nested) {
if (nested.HasProperties || nested.HasEvents)
- return false;
-
- if (nested.Fields.Count == 1) {
- // 4.2+ (maybe 4.0+)
-
- if (!MemberReferenceHelper.compareTypes(nested.Fields[0].FieldType, nested))
- return false;
-
- if (DotNetUtils.getMethod(nested, "System.Reflection.Emit.MethodBuilder", "(System.Reflection.Emit.TypeBuilder)") == null)
- return false;
- }
- else if (nested.Fields.Count == 2) {
- // 3.5 and maybe earlier
-
- var field1 = nested.Fields[0];
- var field2 = nested.Fields[1];
- if (field1.FieldType.FullName != "System.Collections.Hashtable" && field2.FieldType.FullName != "System.Collections.Hashtable")
- return false;
- if (!MemberReferenceHelper.compareTypes(field1.FieldType, nested) && !MemberReferenceHelper.compareTypes(field2.FieldType, nested))
- return false;
- }
- else
- return false;
+ return null;
if (DotNetUtils.getMethod(nested, ".ctor") == null)
- return false;
- if (DotNetUtils.getMethod(nested, "System.String", "(System.Int32)") == null)
- return false;
+ return null;
+ if (nested.Fields.Count == 1) {
+ // 4.0+
+
+ if (!MemberReferenceHelper.compareTypes(nested.Fields[0].FieldType, nested))
+ return null;
+
+ if (DotNetUtils.getMethod(nested, "System.Reflection.Emit.MethodBuilder", "(System.Reflection.Emit.TypeBuilder)") == null)
+ return null;
+
+ var nestedDecrypter = DotNetUtils.getMethod(nested, "System.String", "(System.Int32)");
+ if (nestedDecrypter == null || nestedDecrypter.IsStatic)
+ return null;
+ var decrypter = DotNetUtils.getMethod(type, "System.String", "(System.Int32)");
+ if (decrypter == null || !decrypter.IsStatic)
+ return null;
+
+ return new DecrypterInfoV2 { Decrypter = decrypter };
+ }
+ else if (nested.Fields.Count == 2) {
+ // 3.0 - 3.5
+
+ if (checkFields(nested, "System.Collections.Hashtable", nested)) {
+ // 3.5
+ var nestedDecrypter = DotNetUtils.getMethod(nested, "System.String", "(System.Int32)");
+ if (nestedDecrypter == null || nestedDecrypter.IsStatic)
+ return null;
+ var decrypter = DotNetUtils.getMethod(type, "System.String", "(System.Int32)");
+ if (decrypter == null || !decrypter.IsStatic)
+ return null;
+
+ return new DecrypterInfoV2 { Decrypter = decrypter };
+ }
+ else if (checkFields(nested, "System.Byte[]", nested)) {
+ // 3.0
+ var nestedDecrypter = DotNetUtils.getMethod(nested, "System.String", "(System.String,System.Int32)");
+ if (nestedDecrypter == null || nestedDecrypter.IsStatic)
+ return null;
+ var decrypter = DotNetUtils.getMethod(type, "System.String", "(System.String,System.Int32)");
+ if (decrypter == null || !decrypter.IsStatic)
+ return null;
+
+ return new DecrypterInfoV1 { Decrypter = decrypter };
+ }
+ else
+ return null;
+ }
+
+ return null;
+ }
+
+ bool checkFields(TypeDefinition type, string fieldType1, TypeDefinition fieldType2) {
+ if (type.Fields.Count != 2)
+ return false;
+ if (type.Fields[0].FieldType.FullName != fieldType1 &&
+ type.Fields[1].FieldType.FullName != fieldType1)
+ return false;
+ if (!MemberReferenceHelper.compareTypes(type.Fields[0].FieldType, fieldType2) &&
+ !MemberReferenceHelper.compareTypes(type.Fields[1].FieldType, fieldType2))
+ return false;
return true;
}
@@ -112,14 +211,14 @@ namespace de4dot.code.deobfuscators.Babel_NET {
return;
if (encryptedResource != null)
return;
- encryptedResource = findResource();
- if (encryptedResource == null)
- return;
- var decrypted = new ResourceDecrypter(module).decrypt(encryptedResource.GetResourceData());
- var reader = new BinaryReader(new MemoryStream(decrypted));
- while (reader.BaseStream.Position < reader.BaseStream.Length)
- offsetToString[(int)reader.BaseStream.Position] = reader.ReadString();
+ if (decrypterInfo.NeedsResource) {
+ encryptedResource = findResource();
+ if (encryptedResource == null)
+ return;
+ }
+
+ decrypterInfo.initialize(module, encryptedResource);
}
EmbeddedResource findResource() {
@@ -133,8 +232,8 @@ namespace de4dot.code.deobfuscators.Babel_NET {
return null;
}
- public string decrypt(int offset) {
- return offsetToString[offset];
+ public string decrypt(object[] args) {
+ return decrypterInfo.decrypt(args);
}
}
}