elmah.axd Disclosure

Manieendar Mohan
Published on
20 Dec 2021


Elmah is an application-wide error logging facility that is completely pluggable.This vulnerability can cause highly sensitive data leaks on current sessions. It is a powerful tool that helps developers debug and resolve problems in their applications.it is configured improperly on target websites, and that allows attackers to gain information about requests and responses to the application. Information such as:

  • Session cookies

  • Session state

  • Query string and post variables

  • Physical path of the requested file

This means that the attacker can hijack any active user’s session by using their session details.


Apply the changes in web.config file to disable remote access to the Elmah.axd error log.

Also uses ASP.NET’s own authorization mechanism to protect Elmah.axd error log from attackers. It makes the Elmah.axd error log viewable by only authorized Administrators.

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Written by
Manieendar Mohan
Manieendar Mohan
Cyber Security Lead Engineer
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