[LAB8] 313551150

lab8/solve.py

@@ -1,11 +1,41 @@
 #!/usr/bin/env python3
-
-import angr,sys
+import angr
+import claripy
+import sys
 
 def main():
-    secret_key = b""
-    sys.stdout.buffer.write(secret_key)
+    # 載入二進位，不載入動態函式庫加快速度
+    proj = angr.Project('./chal', auto_load_libs=False)
+
+    # 建立 8 個符號字元
+    flag_chars = [claripy.BVS(f'c{i}', 8) for i in range(8)]
+    flag = claripy.Concat(*flag_chars)
+
+    # 製作帶有符號輸入的初始狀態
+    # has_end=True 表示讀到 flag 後即結束輸入
+    stdin = angr.SimFileStream(name='stdin', content=flag, has_end=True)
+    state = proj.factory.full_init_state(stdin=stdin)
+
+    # 限制每個字元為可列印 ASCII（32~126）
+    for c in flag_chars:
+        state.solver.add(c >= 0x20)
+        state.solver.add(c <= 0x7e)
+
+    simgr = proj.factory.simulation_manager(state)
+
+    # 尋找印出「Correct! The flag is」的路徑
+    target = b"Correct! The flag is"
+    simgr.explore(find=lambda s: target in s.posix.dumps(1))
 
+    if simgr.found:
+        found = simgr.found[0]
+        # 求解出具體 key
+        solution = found.solver.eval(flag, cast_to=bytes)
+        # 輸出到 stdout，供 validate.sh 傳給 chal
+        sys.stdout.buffer.write(solution)
+    else:
+        print("No solution found.", file=sys.stderr)
+        sys.exit(1)
 
 if __name__ == '__main__':
     main()