詳解各種PHP函數(shù)漏洞

0x01 md5(str)
    QNKCDZO
    240610708
    s878926199a
    s155964671a
    s214587387a
    s214587387a
     sha1(str)
    sha1('aaroZmOk')  
    sha1('aaK1STfY')
    sha1('aaO8zKZF')
    sha1('aa3OFF9m')

0x02 md5(md5(str)."SALT")
    2

if(@md5($_GET['a']) == @md5($_GET['b']))
{
    echo "yes";
}
//http://127.0.0.1/1.php?a[]=1b[]=2

?php

//key.php?aaaa'aaa=1bb'b=2 

//print_R($_GET); 

 foreach ($_GET AS $key => $value)

{

        print $key."\n";

}

?>

?php  
    $auth = '0';  
    // 這里可以覆蓋$auth的變量值
    extract($_GET); 
    if($auth == 1){  
        echo "private!";  
    } else{  
        echo "public!";  
    }  
?>

?php  
$a='hi';
foreach($_GET as $key => $value) {
        echo $key;
        $$key = $value;
}
print $a;
?>

?php
    $password=$_GET['password'];
    if (strcmp('xd',$password)) {
     echo 'NO!';
    } else{
        echo 'YES!';
    }
?>

if (@sha1([]) ==  false)
    echo 1;
if (@md5([]) ==  false)
    echo 2;
echo var_dump(@sha1([]));

?php
echo is_numeric(233333);       # 1
echo is_numeric('233333');    # 1
echo is_numeric(0x233333);    # 1
echo is_numeric('0x233333');   # 1
echo is_numeric('233333abc');  # 0
?>

?php
$ip = '1.1.1.1 abcd'; // 可以繞過(guò)
if(!preg_match("/(\d+)\.(\d+)\.(\d+)\.(\d+)/",$ip)) {
  die('error');
} else {
   echo('key...');
}
?>

//var.php?var=new  
$var='init';  
parse_str($_SERVER['QUERY_STRING']);  
print $var;

?php  
echo 0 == 'a' ;// a 轉(zhuǎn)換為數(shù)字為 0    重點(diǎn)注意

// 0x 開(kāi)頭會(huì)被當(dāng)成16進(jìn)制54975581388的16進(jìn)制為 0xccccccccc
// 十六進(jìn)制與整數(shù)，被轉(zhuǎn)換為同一進(jìn)制比較
'0xccccccccc' == '54975581388' ;
// 字符串在與數(shù)字比較前會(huì)自動(dòng)轉(zhuǎn)換為數(shù)字，如果不能轉(zhuǎn)換為數(shù)字會(huì)變成0
1 == '1';
1 == '01';
10 == '1e1';
'100' == '1e2' ;    

// 十六進(jìn)制數(shù)與帶空格十六進(jìn)制數(shù)，被轉(zhuǎn)換為十六進(jìn)制整數(shù)
'0xABCdef'  == '     0xABCdef';
echo '0010e2' == '1e3';
// 0e 開(kāi)頭會(huì)被當(dāng)成數(shù)字，又是等于 0*10^xxx=0
// 如果 md5 是以 0e 開(kāi)頭，在做比較的時(shí)候，可以用這種方法繞過(guò)
'0e509367213418206700842008763514' == '0e481036490867661113260034900752';
'0e481036490867661113260034900752' == '0' ;

var_dump(md5('240610708') == md5('QNKCDZO'));
var_dump(md5('aabg7XSs') == md5('aabC9RqS'));
var_dump(sha1('aaroZmOk') == sha1('aaK1STfY'));
var_dump(sha1('aaO8zKZF') == sha1('aa3OFF9m'));
?>

?php  
// http://127.0.0.1/index.php?_CONFIG=123
$_CONFIG['extraSecure'] = true;

foreach(array('_GET','_POST') as $method) {
    foreach($$method as $key=>$value) {
      // $key == _CONFIG
      // $$key == $_CONFIG
      // 這個(gè)函數(shù)會(huì)把 $_CONFIG 變量銷(xiāo)毀
      unset($$key);
    }
}

if ($_CONFIG['extraSecure'] == false) {
    echo 'flag {****}';
}
?>

$var = 5;  
方式1：$item = (string)$var;  
方式2：$item = strval($var); 

var_dump(intval('2')) //2  
var_dump(intval('3abcd')) //3  
var_dump(intval('abcd')) //0 

?php  
$a = '10000 union select * from yz';
if(intval($a)>1000)   
    echo $a ;
?>

?php
$i ="2abc";  
switch ($i) {  
case 0:  
case 1:  
case 2:  
echo "i is less than 3 but not negative";  
break;  
case 3:  
echo "i is 3";  
} 
?>

$array=[0,1,2,'3'];  
var_dump(in_array('abc', $array)); //true  
var_dump(in_array('1bc', $array)); //true 

?php
class test
{
    public $username = '';
    public $password = '';
    public $file = '';
    public function out(){
        echo "username: ".$this->username."br>"."password: ".$this->password ;
    }
     public function __toString() {
        return file_get_contents($this->file);
    }
}
$a = new test();
$a->file = 'C:\Users\YZ\Desktop\plan.txt';
echo serialize($a);
?>
//tostring方法會(huì)在輸出實(shí)例的時(shí)候執(zhí)行，如果實(shí)例路徑是隱秘文件就可以讀取了

?php
class test
{
    public $username = '';
    public $password = '';
    public $file = '';
    public function out(){
        echo "username: ".$this->username."br>"."password: ".$this->password ;
    }
     public function __toString() {
        return file_get_contents($this->file);
    }
}
$a = 'O:4:"test":3:{s:8:"username";s:0:"";s:8:"password";s:0:"";s:4:"file";s:28:"C:\Users\YZ\Desktop\plan.txt";}';
echo unserialize($a);
?>

?php
ini_set('session.serialize_handler', 'php_serialize');//a:1:{s:6:"spoock";s:3:"111";}
//ini_set('session.serialize_handler', 'php');//a|s:3:"111"
session_start();
$_SESSION["spoock"]=$_GET["a"];
?>

spoock|s:3:"111";    //session鍵值|內(nèi)容序列化
a:1:{s:6:"spoock";s:3:"111";}a:1:{s:N:session鍵值;內(nèi)容序列化}
在ini_set('session.serialize_handler', 'php');中把|之前認(rèn)為是鍵值后面的視為序列化
那么就可以利用這一漏洞執(zhí)行一些惡意代碼

?php
ini_set('session.serialize_handler', 'php_serialize');
session_start();
$_SESSION["spoock"]=$_GET["a"];
?>

?php
   ini_set('session.serialize_handler', 'php');
session_start();
class lemon {
    var $hi;
    function __construct(){
        $this->hi = 'phpinfo();';
    }

    function __destruct() {
         eval($this->hi);//這里很危險(xiǎn)，可以執(zhí)行用戶(hù)輸入的參數(shù)
    }
}
?>