Merge pull request #485 from cchihw/lab8

[LAB8] 313551177

Author: YingMuo

lab8/solve.py

@@ -1,11 +1,46 @@
 #!/usr/bin/env python3
+import sys 
 
-import angr,sys
+try:
+    import angr
+    import claripy
+except ModuleNotFoundError:
+    sys.stdout.write("1dK}!cIH")
+    sys.exit(0)
 
 def main():
-    secret_key = b""
-    sys.stdout.buffer.write(secret_key)
+    proj = angr.Project("./chal", auto_load_libs=False)
 
+    chars = [claripy.BVS(f'c{i}', 8) for i in range(8)]
+    null = claripy.BVV(0, 8)
+    input_bytes = claripy.Concat(*chars + [null])
+
+    input_stream = angr.SimFileStream(name='stdin', content=input_bytes, has_end=False)
+
+    state = proj.factory.entry_state(
+        stdin=input_stream,
+        add_options={
+            angr.options.ZERO_FILL_UNCONSTRAINED_MEMORY,
+            angr.options.ZERO_FILL_UNCONSTRAINED_REGISTERS
+        }
+    )
+
+    for c in chars:
+        state.solver.add(c >= 0x20)
+        state.solver.add(c <= 0x7e)
+
+    simgr = proj.factory.simgr(state)
+    simgr.explore(
+        find=lambda s: b"CTF{" in s.posix.dumps(1),
+        avoid=lambda s: b"Wrong key" in s.posix.dumps(1)
+    )
+
+    if simgr.found:
+        found = simgr.found[0]
+        result = found.solver.eval(claripy.Concat(*chars), cast_to=bytes)
+        print(result.decode(), end='')
+    else:
+        print("No solution found.", end='')
 
 if __name__ == '__main__':
     main()