Questions tagged [regex]

security concerns around regular expressions; using them as security-critical filters, processing user-supplied regexes, vulnerabilities in regex parsers, etc.

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How do I bypass a regex filter that filters all html to avoid xss?

How do I bypass a regex filter that filters all html to avoid xss? I've tried using things like <img src="aa" onerror="alert(1)"> but still no luck. This is for a CTF ...
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2answers
200 views

Is it possible to exploit preg_match similar to preg_replace PHP? [closed]

I'm currently working on a website and want to prevent characters being inputted, i am using following code if (!preg_match("/^[a-zA-Z0-9_!,()& -\/]*$/" is it possible to exploit this ...
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3answers
215 views

Mailcleaner - Fail2ban - mc-exim-filter configuration

I'm using Fail2ban on a Mailcleaner server which works pretty good, but I want to update it to ban hosts who want to spoof our addresses. I'm using the "original" mc-exim-filter, but I don't ...
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1answer
91 views

Email pattern ReDoS

I would like to verify that the input from the user complies to the format of email address (in Java application). On the following page there is verbose regex that should properly validate the email ...
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1answer
674 views

Source of RegEx examples of Secret Detection patterns in repositories?

Where can I find RegEx that can pattern match common secret strings? I have a product that scans repos and commits and in case a developer tries to commit a secret (i.e. passwords, keys). It scans for ...
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1answer
254 views

Possible to bypass this regex for XSS?

When testing for XSS, is it at all possible to bypass the below regex? I doubt it because it only accepts uppercase and lowercase letters, but maybe? /^[A-Za-z]+$/
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0answers
38 views

Is it safe to pass user input through rails gsub?

Are there risks associated with using gsub on user input? Can it be used for regular expression DoS?
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0answers
139 views

Regex DoS: Is OWASP's characterization of "evil regexes" complete?

OWASP defines "evil regex" (here) as follows: Evil Regexes A Regex is called "evil" if it can stuck on crafted input. Evil Regex pattern contains: Grouping with repetition ...
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1answer
129 views

What is the following regex trying to protect against?

I am looking at a Java web application that compares all incoming request params and cookies against the following regex. If it matches, it is considered "an attack" and refuses the request. I'm ...
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0answers
2k views

OAuth access token/API key patterns for large web sites

First off, let me preface this post by saying I'm not a security expert. I'm trying to build regular expressions to find OAuth 2.0 access tokens and API Keys for common web sites such as Google, ...
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0answers
468 views

What is the risk of allowing user input in Python's 're' module

Some context I'm currently building an application which lets user's set up dynamic, queries they can execute later. A great addition to this seems like a regex module, in which users can filter ...
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0answers
2k views

Boolean blind SQLi with sqlmap

I am trying to run sqlmap in order to find a flag for a CTF. The injection string is sent via a POST request in the parameter called search. The response is received as either 1, 2, or 3 (error codes),...
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0answers
177 views

Can a Regex without characters [(+*{}? be dangerous?

I want to create some functionality for non dangerous regex. I want to accept only very few regex cases where it is safe to assume that they are not malicious (but still giving the user some ...
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1answer
41 views

How to filter HTML Event in Native PHP7

i want to creating xss filter for my own project, this is for html event filtering preg_replace("/ on\w+='[^']*'/i", '', preg_replace('/ on\w+="[^"]*"/i', '', $framed)); but considering to more ...
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1answer
326 views

Is this regular expression vulnerable to DoS?

FindBugs flagged the following email address validation regex as vulnerable to DoS: ^[\w!#$%&'*+/=?`{|}~^-]+(?:\.[\w!#$%&'*+/=?`{|}~^-]+)*@(?:[a-zA-Z0-9-]+\.)+[a-zA-Z]{2,6}$ Here's an easier ...
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7answers
28k views

Is it possible to detect 100% of SQLi with a simple regex?

I'm wondering if it is possible to detect 100% of the possible SQLi attacks using a simple regex. In other words, using very simple PHP code as an example: if (preg_match("/select/i", $input)) { ...
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1answer
1k views

What are the common features to identify Brute-Force attack from Apache log file?

There are various methods to find attack patterns for different types of attacks. Apache-scalp is one such tool, but the rule set is not available to find the brute-force attack pattern via regular ...
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1answer
93 views

Alternative forms for special characters in terminal

I was solving a problem on a popular hacking for fun website, when I got following idea: Is it possible to represent - for example a '/' (just the slash) in the terminal (linux) in another way - for ...
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6answers
19k views

Is it safe to let a user type a regex as a search input?

I was in a mall a few days ago and I searched for a shop on an indication panel. Out of curiosity, I tried a search with (.+) and was a bit surprised to get the list of all the shops in the mall. I'...
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0answers
971 views

Brute force hex password with exactly two special characters using JohnTheRipper

I want to optimize the way I'm using John the Ripper. I have a password with a know length (9) that consists only of (lower-case) hex characters and exactly two special characters. First I tried ...