I have been doing PHP development for so long and I have never really paid attention to security issues. I always focus on completing the project. Recently I saw an article about security on the Internet. After reading it, I noticed that I had previously All the projects had big security vulnerabilities, so I picked one project and tested it, and found that it was easy to get caught. Here I will share a test example I wrote to illustrate how the session in PHP is unsafe and how to strengthen its security in the project.
Regarding the principle and mechanism of session, there are many good articles on the Internet to introduce it, and we can check it by ourselves. Let’s share examples for testing directly.
The example of this test is mainly a login page. After successful login, you can change the password. It is such a simple function.
The interface is as follows
First, use the function session_start() at the project entrance to open the session. In this way, when the client initiates a request, an identity identifier, namely SessionID, will be generated. It is saved on the client through a cookie. Each communication between the client and the server relies on this SessionID for identification.
After successful login, the user ID and user name will be stored in the session
$_SESSION[‘userid'] = 用户id $_SESSION[‘uname'] = 用户名
All future operations will check whether the user is logged in by judging whether $_SESSION['userid'] exists. The code is as follows:
if(isset($_SESSION['userid'])) return true;
The call to the password modification interface transmits data to the server through ajax post.
$.post("接口*******",
{
oldpass:oldpass,
newpass:newpass,
userid:uid,
},
function(data){
data = eval('(' +data+ ')');
$('.grant_info').html(infos[data.info]).show();
}
);
Note that I have written this code in the html page, so if you see the html code, you will know the interface address.
The interface for changing the password is implemented in this way. First, it is judged whether the user is logged in. If the user is logged in, the password modification operation will be performed.
The implementation idea of the test example is roughly as described above.
Using SessionID Attack
1. The first is to obtain the SessionID. Of course, there are many ways for attackers to obtain this ID. Due to my limited level, I will not introduce how to obtain it here. We can simulate it by first accessing this project normally, and then checking the SessionID through the browser to get a legal user ID. This ID can be seen in the request header
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Encoding: gzip, deflate Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3 Connection: keep-alive Cookie: Hm_lvt_bf1154ec41057869fceed66e9b3af5e7=1450428827,1450678226,1450851291,1450851486; PHPSESSID=2eiq9hcpu3ksri4r587ckt9jt7; Host: ****** Referer: ****** User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:41.0) Gecko/20100101 Firefox/41.0
After getting the session ID, if the user logs in successfully, then the user's information will be in the session on the server side.
2. After obtaining the SessionID, if the attacker already knows the interface for changing the password, he can directly change the user's password. If the attacker has not yet obtained the interface address, he or she can find out the interface address by looking at the page code. You can use the following command
#curl --cookie "PHPSESSID=2eiq9hcpu3ksri4r587ckt9jt7" 页面地址
As we said above, in this example the ajax code is written in the html page, so the interface address can be viewed on this page
Part of the html code is as follows
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
……
var uid = $(".userid").val();
$.post("/User/User/modifypass_do",
{
oldpass:oldpass,
newpass:newpass,
userid:uid,
},
function(data){
data = eval('(' +data+ ')');
$('.grant_info').html(infos[data.info]).show();
}
);
……
<span><input type="password" name="oldpass" id="textfield_o" placeholder="原密码"></span>
<span><input type="password" name="newpass" id="textfield_n" placeholder="新密码"></span>
<span><input type="password" name="confirmpass" id="textfield_c" placeholder="确认密码"></span>
<input type="button" class="btn_ok" value="确认修改" />
3. After getting the interface, you can use curl to simulate post to send data to change the password
The command is as follows
# curl --cookie "PHPSESSID=2eiq9hcpu3ksri4r587ckt9jt7" -d oldpass=111111 -d newpass=000000 -d userid=用户id 接口地址
If this user is already logged in, the attacker can change the user's password by executing the above command.
Solution
For the above attacks, we can enhance its security by complicating the verification method. One way is to use the User-Agent item in the request header to enhance its security
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Encoding: gzip, deflate Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3 Connection: keep-alive Cookie: Hm_lvt_bf1154ec41057869fceed66e9b3af5e7=1450428827,1450678226,1450851291,1450851486; PHPSESSID=2eiq9hcpu3ksri4r587ckt9jt7; Host: ****** Referer: ****** User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:41.0) Gecko/20100101 Firefox/41.0
At the beginning of the project, we just used the session_start() function to start the session. Now we can add this code below session_start()
$_SESSION[‘User_Agent'] = md5($_SERVER[‘HTTP_USER_AGENT']);
Then every time when judging whether to log in, add the following judgment conditions
If(isset($_SESSION[‘userid']) && $_SESSION[‘User_Agent'] == md5($_SERVER[‘HTTP_USER_AGENT'])){
return true;
}
This way you can avoid the simple attacks mentioned above.
Summary:
Of course, the actual attack is far from that simple. First, it is difficult to obtain the SessionID. Then, the code interacting with the server must be encrypted as much as possible to avoid the above situation. After we modify the code for the second time, we can increase the complexity of the attack, but it cannot eliminate the attack. There are many ways to attack. This is just a simple way and only provides one idea, but the principle is the same. In actual situations, the security of our code can be enhanced according to the actual situation.
Here I am just sharing the problems I encountered at work, and I hope everyone can learn more in depth.
php怎么把负数转为正整数Apr 19, 2022 pm 08:59 PMphp把负数转为正整数的方法：1、使用abs()函数将负数转为正数，使用intval()函数对正数取整，转为正整数，语法“intval(abs($number))”；2、利用“~”位运算符将负数取反加一，语法“~$number + 1”。
php怎么实现几秒后执行一个函数Apr 24, 2022 pm 01:12 PM实现方法：1、使用“sleep(延迟秒数)”语句，可延迟执行函数若干秒；2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句，可延迟执行函数若干秒和纳秒；3、使用“time_sleep_until(time()+7)”语句。
php怎么除以100保留两位小数Apr 22, 2022 pm 06:23 PMphp除以100保留两位小数的方法：1、利用“/”运算符进行除法运算，语法“数值 / 100”；2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值，并保留两位小数。
php怎么根据年月日判断是一年的第几天Apr 22, 2022 pm 05:02 PM判断方法：1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式；2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的，因此真实天数需要在此基础上加1。
php字符串有没有下标Apr 24, 2022 am 11:49 AMphp字符串有下标。在PHP中，下标不仅可以应用于数组和对象，还可应用于字符串，利用字符串的下标和中括号“[]”可以访问指定索引位置的字符，并对该字符进行读写，语法“字符串名[下标值]”；字符串的下标值（索引值）只能是整数类型，起始值为0。
php怎么读取字符串后几个字符Apr 22, 2022 pm 08:31 PM在php中，可以使用substr()函数来读取字符串后几个字符，只需要将该函数的第二个参数设置为负值，第三个参数省略即可；语法为“substr(字符串,-n)”，表示读取从字符串结尾处向前数第n个字符开始，直到字符串结尾的全部字符。
php怎么替换nbsp空格符Apr 24, 2022 pm 02:55 PM方法：1、用“str_replace(" ","其他字符",$str)”语句，可将nbsp符替换为其他字符；2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。
php怎么判断有没有小数点Apr 20, 2022 pm 08:12 PMphp判断有没有小数点的方法：1、使用“strpos(数字字符串,'.')”语法，如果返回小数点在字符串中第一次出现的位置，则有小数点；2、使用“strrpos(数字字符串,'.')”语句，如果返回小数点在字符串中最后一次出现的位置，则有。
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
SublimeText3 English version
Recommended: Win version, supports code prompts!
Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.
Zend Studio 13.0.1
Powerful PHP integrated development environment
DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software
mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
