PHP anti-injection attack experience
1:
This topic is too cliché.
Set magic_quotes_gpc = On in PHP.INI
It can indeed prevent some injection attacks, but is it omnipotent?
We are now converting the variables received by POST or GET, converting the spaces, punctuation marks, and special characters into HTML encoding.
I will restore it during the demonstration. How did you do it? Share the code.
But it’s still useless. You can’t prevent union statements when your SQL is not written in a standardized way.
For example, select * from news where id=$Id, if the variable $Id is not enclosed in small quotation marks, and it is not determined whether the $Id is a numeric string, it will definitely be injected, even if magic_quotes_gpc = On.
The only way to completely prevent injection is to enclose the variables in small quotes within the SQL statement, and then
magic_quotes_gpc = On, then convert spaces, punctuation marks, and special characters into HTML encoding.
I think this will solve it once and for all. I don’t know if there are any fish that have slipped through the net. Please give me some advice. If the system we are developing now eliminates injection, then I can sleep well. Haha.
Generally, I use functions directly on each page to preliminarily filter _get, _post, _session and other data
Force checking of data type when writing to database~
Basically these are good for general injection effects
1 SQL statements are best formatted through sprintf, and then query
2 When doing login testing, it is best to use one value to get another value, and then compare it
Example:
Haha, that’s an example I gave. I summarized it carefully, it is very easy not to be injected.
The summary is as follows:
magic_quotes_gpc = On is turned on, and then the variable is enclosed in small quotation marks. If someone wants to inject it, they have to break through the quotation marks, so they have to add small quotation marks to the variable. Adding small quotation marks will be escaped by magic_quotes_gpc = On. Breaking through is small Quotes failed. You can't do bad things.
Another point is that there are two comment marks in MYSQL, # and /*. Through this, the following SQL language name can be commented out, and these two characters can be converted into ASC code or HTML code.
Then the parent who injects the attack is the space.
For example, select * from news where id=1 union select * from admin, if I delete or convert the spaces.
It becomes select * from news where id=1unionselect*fromadmin, which is the result of stealing data.
select * from news where id=1; drop table news remove the spaces here.
select * from news where id=1; droptablenews cannot be executed.
So the parents of injection attacks are spaces. After spaces are replaced. I can really sleep peacefully

php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”。

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。

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。

php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。

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。

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。


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