reflected XSS scripting

[Zsolt Edelényi]

Hello,

One of my ethic hacker discovered a reflected XSS vulnerability by injecting the following code to the end of the location URL:

/?%2522%253e%253cscript%253ealert%2528location%2529%253c%252fscript%253e

I wonder if I install BPS or BPS Pro would filter such an attack?

Regards,

Zsolt

[AITpro Admin]

I would need to know how the attack is performed to give you an answer.

Example How to test: > https://owasp.org/www-project-web-security-testing-guide/v41/4-Web_Application_Security_Testing/07-Input_Validation_Testing/01-Testing_for_Reflected_Cross_Site_Scripting.html
Step 1 do x
Step 2 do y
Step 3 do z

Examples:

This usage would be blocked by BPS
https://www.ait-pro.com/wp-config.php?user=%2522%253e%253cscript%253ealert%2528location%2529%253c%252fscript%253e

This usage would not be blocked by BPS because it is harmless
https://www.ait-pro.com/index.php?user=%2522%253e%253cscript%253ealert%2528location%2529%253c%252fscript%253e

[Zsolt Edelényi]

Hi Admin,

Thank you. I’ve started to understand what you expect. Would you please help me? I’d like to understand:

• What does it mean %2522%253e% etc?
• What if we want to disable all reflected XSS not only the harming ones?
• the following attackers’s code would be removed by BPS PRO?/?%2522%253e%253cscript%253ealert%2528location%2529%253c%252fscript%253e

Best Regards,

Zsolt

[AITpro Admin]

See this URL Encoding chart > https://en.wikipedia.org/wiki/Percent-encoding to translate the URL encoded characters.

You can create a custom Query String rule and add it to the BPS Query String Exploits code saved in this BPS Root Custom Code text box:  12. CUSTOM CODE BPSQSE BPS QUERY STRING EXPLOITS.

Example:

You would add a custom Query String Exploits rule somewhere within the BPS Query String Exploits code.  Note: BPS already protects against actual Reflected XSS attacks if they are harmful.  You would not need to block Reflected XSS attacks if they are not harmful.  Example: If a gun is pointed at you that is dangerous.  If a gun is not pointed at you then it is not dangerous.

# BEGIN BPSQSE BPS QUERY STRING EXPLOITS
# The libwww-perl User Agent is forbidden - Many bad bots use libwww-perl modules, but some good bots use it too.
# Good sites such as W3C use it for their W3C-LinkChecker.
# Use BPS Custom Code to add or remove user agents temporarily or permanently from the
# User Agent filters directly below or to modify/edit/change any of the other security code rules below.
RewriteCond %{HTTP_USER_AGENT} (havij|libwww-perl|wget|python|nikto|curl|scan|java|winhttp|clshttp|loader) [NC,OR]
RewriteCond %{HTTP_USER_AGENT} (%0A|%0D|%27|%3C|%3E|%00) [NC,OR]
RewriteCond %{HTTP_USER_AGENT} (;|<|>|'|"|\)|\(|%0A|%0D|%22|%27|%28|%3C|%3E|%00).*(libwww-perl|wget|python|nikto|curl|scan|java|winhttp|HTTrack|clshttp|archiver|loader|email|harvest|extract|grab|miner) [NC,OR]
RewriteCond %{THE_REQUEST} (\?|\*|%2a)+(%20+|\\s+|%20+\\s+|\\s+%20+|\\s+%20+\\s+)(http|https)(:/|/) [NC,OR]
RewriteCond %{THE_REQUEST} etc/passwd [NC,OR]
RewriteCond %{THE_REQUEST} cgi-bin [NC,OR]
RewriteCond %{THE_REQUEST} (%0A|%0D|\\r|\\n) [NC,OR]
RewriteCond %{REQUEST_URI} owssvr\.dll [NC,OR]
RewriteCond %{HTTP_REFERER} (%0A|%0D|%27|%3C|%3E|%00) [NC,OR]
RewriteCond %{HTTP_REFERER} \.opendirviewer\. [NC,OR]
RewriteCond %{HTTP_REFERER} users\.skynet\.be.* [NC,OR]
RewriteCond %{QUERY_STRING} [a-zA-Z0-9_]=(http|https):// [NC,OR]
RewriteCond %{QUERY_STRING} [a-zA-Z0-9_]=(\.\.//?)+ [NC,OR]
RewriteCond %{QUERY_STRING} [a-zA-Z0-9_]=/([a-z0-9_.]//?)+ [NC,OR]
RewriteCond %{QUERY_STRING} \=PHP[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12} [NC,OR]
RewriteCond %{QUERY_STRING} (\.\./|%2e%2e%2f|%2e%2e/|\.\.%2f|%2e\.%2f|%2e\./|\.%2e%2f|\.%2e/) [NC,OR]
RewriteCond %{QUERY_STRING} ftp\: [NC,OR]
RewriteCond %{QUERY_STRING} (http|https)\: [NC,OR]
RewriteCond %{QUERY_STRING} \=\|w\| [NC,OR]
RewriteCond %{QUERY_STRING} ^(.*)/self/(.*)$ [NC,OR]
RewriteCond %{QUERY_STRING} ^(.*)cPath=(http|https)://(.*)$ [NC,OR]
RewriteCond %{QUERY_STRING} (\<|%3C).*script.*(\>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} (<|%3C)([^s]*s)+cript.*(>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} (\<|%3C).*embed.*(\>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} (<|%3C)([^e]*e)+mbed.*(>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} (\<|%3C).*object.*(\>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} (<|%3C)([^o]*o)+bject.*(>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} (\<|%3C).*iframe.*(\>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} (<|%3C)([^i]*i)+frame.*(>|%3E) [NC,OR]
RewriteCond %{QUERY_STRING} base64_encode.*\(.*\) [NC,OR]
RewriteCond %{QUERY_STRING} base64_(en|de)code[^(]*\([^)]*\) [NC,OR]
RewriteCond %{QUERY_STRING} GLOBALS(=|\[|\%[0-9A-Z]{0,2}) [OR]
RewriteCond %{QUERY_STRING} _REQUEST(=|\[|\%[0-9A-Z]{0,2}) [OR]
RewriteCond %{QUERY_STRING} ^.*(\(|\)|<|>|%3c|%3e).* [NC,OR]
RewriteCond %{QUERY_STRING} ^.*(\x00|\x04|\x08|\x0d|\x1b|\x20|\x3c|\x3e|\x7f).* [NC,OR]
RewriteCond %{QUERY_STRING} (NULL|OUTFILE|LOAD_FILE) [OR]
RewriteCond %{QUERY_STRING} (\.{1,}/)+(motd|etc|bin) [NC,OR]
RewriteCond %{QUERY_STRING} (localhost|loopback|127\.0\.0\.1) [NC,OR]
RewriteCond %{QUERY_STRING} (<|>|'|%0A|%0D|%27|%3C|%3E|%00) [NC,OR]
RewriteCond %{QUERY_STRING} concat[^\(]*\( [NC,OR]
RewriteCond %{QUERY_STRING} union([^s]*s)+elect [NC,OR]
RewriteCond %{QUERY_STRING} union([^a]*a)+ll([^s]*s)+elect [NC,OR]
RewriteCond %{QUERY_STRING} \-[sdcr].*(allow_url_include|allow_url_fopen|safe_mode|disable_functions|auto_prepend_file) [NC,OR]
RewriteCond %{QUERY_STRING} (;|<|>|'|"|\)|%0A|%0D|%22|%27|%3C|%3E|%00).*(/\*|union|select|insert|drop|delete|update|cast|create|char|convert|alter|declare|order|script|set|md5|benchmark|encode) [NC,OR]
RewriteCond %{QUERY_STRING} (sp_executesql) [NC]
RewriteRule ^(.*)$ - [F]
# END BPSQSE BPS QUERY STRING EXPLOITS

[Zsolt Edelényi]

Thank you.

[Author]

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