https:// host:port로 서버에 접속한다.
f12로 소스 코드를 확인해 보면
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Welcome</title>
</head>
<body>
<h1>Welcome! 👋</h1>
<form method="POST">
<input type="hidden" name="64se64_encoding" value="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">
</form>
</body>
</html>base64로 디코딩하면 파이썬 코드가 나온다.
#!/usr/bin/env python3
asc=[68, 72, 123, 98, 101, 48, 52, 54, 98, 55, 53, 50, 50, 97, 97, 50, 101, 50, 56, 102, 50, 55, 54, 101, 48, 99, 57, 49, 48, 53, 50, 49, 102, 50, 51, 97, 48, 53, 56, 55, 48, 48, 53, 97, 56, 51, 55, 55, 51, 55, 48, 97, 49, 49, 101, 53, 101, 52, 100, 99, 49, 53, 102, 98, 50, 97, 98, 125]
arr=[0 for i in range(68)]
for i in range(0,68):
arr[i]=chr(asc[i])
flag=''.join(arr)
print(flag)Visual studio로 코드를 실행하면 Flag 찾기 끝!
