b01lers(php.galf)

前文

正文

前文

<?phpclass A{public $code=NULL;public $args=NULL;public function __construct($code,$args=NULL){$this->code=$code;$this->args=$args;print_r("2333") ;}
public function __invoke($code,$args){echo $code;print_r("执行invoke") ;}
}
$B=new A(55,66);
$B(33,44);

233 333执行invoke说明执行了construct和invoke

 throw new A(55, 100);也会对construct进行初始化

然后肯定是从index.php开始出发，php文件不算太多，可以逐个看一下出口也就是能够命令执行获得flag的地方。

最终可以在noitpecxe.php下面找到可疑点，因为这俩参数还是构造函数传进来的，也就是说我们可以通过调用实参来操作。

正文

index.php

<?phpdefine('block', TRUE);require("parser/syntaxreader.php");include("flag.php");$code = "ohce ohce ohce ohce ohce ohce ohce";$args = "flag.php,aaa,aaa,highlight_file,orez_lum,orez_vid,syntaxreader";$result = NULL;if (!isset($_COOKIE['DEBUG'])){//如果cookie中不存在，DEBUG$result = new syntaxreader($code, $args);} else if (strcmp($_COOKIE['DEBUG'], hash("md5")) == 0) {echo "Warning: Adming debugging enabled!";$result = new syntaxreader($code, $args, NULL);} else {$debug = array("Debugging Enabled!", 69);$result = new syntaxreader($code, $args, $debug);}$result->run();?>

这里code args是post传参可控，我这里直接把答案先写出来方便理解。

这里肯定会调用 syntaxreader的构造函数，看了一下三者的区别，其实就是末尾的debug传参的问题，第一个if和第二个elseif都是NULL，但是第三个确有值，这是唯一的差别。

syntaxreader.php

public function __construct($lines, $args, $debug = NULL) {$this->code = explode("\n", $lines);//这里使用\n作为分隔符号，切成数组$this->args = $args;$this->result = $result;if (isset($debug)) {//这里不可能执行到的// disable debugging modethrow new noitpecxe(...$debug);}}

如果debug为true的话那么就可以直接初始化noipecxe，然后这里正好是我们一开始想到的漏洞点，直接让$error_func($this->message); ==== hightlight(flag.php)

这里说明一下数组传参， $debug数组传参就会把参数逐个给形参也就是

（message,code,previous,error_func)

(flag.php,aa,aa,highlight)

noipecxe.php

<?php
class noitpecxe extends Exception
{public $error_func = NULL;public function __construct($message, $code, $previous = null, $error_func = "printf") {// remove when PHP 5.3 is no longer supported$this->error_func = $error_func;//printf$this->message = $message;//args的值，是个数组$previous = NULL;//dont care what ur code is LOL!$code = 69;parent::__construct($message, $code, $previous);}public function __toString() {$error_func = $this->error_func;//这里引用到了另一个函数$error_func($this->message);return __CLASS__ . ": {$this->code}\n";}
}
?>

$result->run(); ：：parse

里面作用就是分割数组，并且code的值一定要一直是oche

public function parse() {$parsable = array("ohce");$arg_val = 0;$code = $this->code;$args = $this->args;$result = $this->result;for ($i = 0; $i < count($code); $i++) {//去掉刚才数组分割中的空格$code[$i] = trim($code[$i]);}$args = explode(",", $args);for ($i = 0; $i < count($args); $i++) {//对传入的args进行,分割且去掉空格$args[$i] = trim($args[$i]);}for ($i = 0; $i < count($code); $i++) {$token = explode(" ", $code[$i]);//通过空格继续分割for ($j = 0; $j < count($token); $j++) {try {if (!in_array($token[$j], $parsable)) {//这里必须要满足里面ohcethrow new noitpecxe("Non-Parsable Keyword!\n", 101);}if ($args[$arg_val] == NULL) {//args传入的不能为空throw new noitpecxe("No Arguments!\n", 990);}if ($args[$arg_val] === "noitpecxe") {//不能是这个的值throw new noitpecxe("No Exceptions!\n", 100);}$class = new $token[$j];//玄机在这里，这里肯定是一个跳转类的东西$class($args, $arg_val);//我们可以根据参数来看调的哪个$arg_val++;} catch (noitpecxe $e) {echo "Error Executing Code! Error: " . $e . "\n";}}

然后就会调用oche.php

  public function __invoke($args, $arg_val) {$this->args = $args[$arg_val];$arg_val++;$parsable = array("orez_lum", "orez_dda");if (in_array($this->args, $parsable)) { // we can run operators in ohce!$class = new $this->args;$this->result = $class($args, $arg_val);} else {$this->result = $this->args;}$this->result = strrev($this->result) . "\n";echo $this->result;}

orez_lum和orez_dda内容几乎一样，调用谁都一样，然后调用orez_vid

为什么要调用它呢，看一下传参值

$class($arg, $arg_val);

orez_vid  ($arg = "div", $arg_val = 0, $result = NULL)

new $arg[$arg_val]("div", $result, $arg);

syntaxreader public function __construct($lines, $args, $debug = NULL)

throw new noitpecxe(...$debug);

public function __construct($message, $code, $previous = null, $error_func = "printf")

所以我们一开始传入的arg就可以一条线的到达我们的执行命令，然后就是看一下中间的条件，只有

$_COOKIE['DEBUG']存在即可和上面的index.php判断一样，ok结束

 public function __invoke($arg = "div", $arg_val = 0, $result = NULL) {if (!isset($_COOKIE['DEBUG'])) {  //just gonna prevent people from using thisthrow new noitpecxe("You need to enable debugging mode to access this!\n", 0);}if ($arg[$arg_val] == NULL) {throw new noitpecxe("No Arguments!\n", 990);}if ($arg[$arg_val] === "noitpecxe") {throw new noitpecxe("No Exceptions!\n", 100);}if (isset($result)) {throw new noitpecxe("No dividing by zero!\n", 0);}// smart to call the constructor so there is an exception! I was a genius!$class = new $arg[$arg_val]("div", $result, $arg);$arg_val++;$this->result = $arg[$arg_val] / 0; // dividing by zero??return $this->result;}