LDAP flap as passwords put at risk

MS fails to RTFM on security, again

A flaw with the way Microsoft allows access to LDAP directories over the Internet could permit crackers to gain passwords and hack into database servers.

The vulnerable function is only available if a server has been configured to support LDAP (Lightweight Directory Access Protocol) over SSL sessions, which security experts said severely limits the scope of the bug, and for which Microsoft has issued a patch.

According to a security notice issued by the software giant, the root cause of the problem is that a under certain conditions a function that permits users to change data attributes of directory principals doesn't check the rights of a requester.

Microsoft admits the upshot of this is that "it could be possible for a user to change any other user's domain login password" though not passwords on local machines.

"An attacker could change another user's password for either of two purposes: to cause a denial of service by preventing the other user from logging on, or in order to log into the user's account and gain any privileges the user had," the notice said.

Any user who can establish a connection with a vulnerable server could exploit the vulnerability, which might allow an attacker to change an administrator's password and gain control of the account.

Deri Jones, security testing director at NTA Monitor, said that LDAP directories storing corporate user directories are commonly for internal use only, and it's rare they would be exposed to other people over the Internet.

This factor and the possibility of blocking the attack at firewall level reduce the scope for widespread chaos arising from the bug, from which Microsoft would do well to draw wider lessons.

"Other vulnerabilities have exploited the fact that in trying to make its products easier to use, Microsoft has not properly thought through how to secure user credentials," said Jones, who said a Web extender bug in January arose from a similarly flawed software development process by Microsoft. ®

External Links

Function Exposed via LDAP over SSL Could Enable Passwords to be Changed
Web Extender flaw

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