> For the complete documentation index, see [llms.txt](https://docs.cooku222.kr/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cooku222.kr/security/web-hacking/webhacking.kr/webhacking.kr-old-24.md).
# \[webhacking.kr] old-24
extract($\_SERVER);\
extract($\_COOKIE);\
$ip = $REMOTE\_ADDR;\
$\_SERVER, $\_COOKIE를 extract()로 변수화하고 있음.\
\
REMOTE\_ADDR는 기본적으로 사용자의 실제 IP를 나타내지만, $\_COOKIE에도 같은 키(REMOTE\_ADDR)가 있으면 덮어씀.
$ip = htmlspecialchars($REMOTE\_ADDR);\
$ip = str\_replace("..",".",$ip);\
$ip = str\_replace("12","",$ip);\
$ip = str\_replace("7.","",$ip);\
$ip = str\_replace("0.","",$ip);\
".." → ".", "12" → "", "7." → "", "0." → "" 순서로 문자열을 조작함.
```
Challenge 24
";
}
?>view-source
```
editthiscookie로 쿠키값을 변경한 후 필터링을 우회한다. -> 127.0.0.1이 되는 값을 구한다.
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