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From Kiran Ayyagari <kayyag...@apache.org>
Subject Re: svn commit: r1692562 - in /directory/apacheds/trunk: interceptors/authn/src/main/java/org/apache/directory/server/core/authn/SimpleAuthenticator.java server-integ/src/test/java/org/apache/directory/server/ppolicy/PasswordPolicyIT.java
Date Sat, 25 Jul 2015 14:31:29 GMT
On Sat, Jul 25, 2015 at 10:25 PM, Lucas Theisen <lucastheisen@pastdev.com>
wrote:

>
> On Jul 25, 2015 10:01 AM, "Kiran Ayyagari" <kayyagari@apache.org> wrote:
> >
> >
> >
> > On Sat, Jul 25, 2015 at 9:54 PM, Lucas Theisen <lucastheisen@pastdev.com>
> wrote:
> >>
> >>
> >> On Jul 25, 2015 9:26 AM, "Kiran Ayyagari" <kayyagari@apache.org> wrote:
> >> >
> >> >
> >> > Lucas,
> >> >
> >> > On Sat, Jul 25, 2015 at 2:11 AM, <lucastheisen@apache.org> wrote:
> >> >>
> >> >> Author: lucastheisen
> >> >> Date: Fri Jul 24 18:11:38 2015
> >> >> New Revision: 1692562
> >> >>
> >> >> URL: http://svn.apache.org/r1692562
> >> >>
> >> >> Log:
> >> >> fixed leak of information when password policy fails authentication
> attempt
> >> >>
> >> >> Modified:
> >> >>
> directory/apacheds/trunk/interceptors/authn/src/main/java/org/apache/directory/server/core/authn/SimpleAuthenticator.java
> >> >>
> directory/apacheds/trunk/server-integ/src/test/java/org/apache/directory/server/ppolicy/PasswordPolicyIT.java
> >> >>
> >> >> Modified:
> directory/apacheds/trunk/interceptors/authn/src/main/java/org/apache/directory/server/core/authn/SimpleAuthenticator.java
> >> >> URL:
> http://svn.apache.org/viewvc/directory/apacheds/trunk/interceptors/authn/src/main/java/org/apache/directory/server/core/authn/SimpleAuthenticator.java?rev=1692562&r1=1692561&r2=1692562&view=diff
> >> >>
> >> >>
> ==============================================================================
> >> >> ---
> directory/apacheds/trunk/interceptors/authn/src/main/java/org/apache/directory/server/core/authn/SimpleAuthenticator.java
> (original)
> >> >> +++
> directory/apacheds/trunk/interceptors/authn/src/main/java/org/apache/directory/server/core/authn/SimpleAuthenticator.java
> Fri Jul 24 18:11:38 2015
> >> >> @@ -25,8 +25,10 @@ import java.security.MessageDigest;
> >> >>  import java.security.NoSuchAlgorithmException;
> >> >>  import java.util.Arrays;
> >> >>
> >> >> +
> >> >>  import javax.naming.Context;
> >> >>
> >> >> +
> >> >>  import org.apache.commons.collections.map.LRUMap;
> >> >>  import
> org.apache.directory.api.ldap.model.constants.AuthenticationLevel;
> >> >>  import
> org.apache.directory.api.ldap.model.constants.LdapSecurityConstants;
> >> >> @@ -45,6 +47,7 @@ import org.apache.directory.server.core.
> >> >>  import org.apache.directory.server.core.api.InterceptorEnum;
> >> >>  import org.apache.directory.server.core.api.LdapPrincipal;
> >> >>  import
> org.apache.directory.server.core.api.authn.ppolicy.PasswordPolicyConfiguration;
> >> >> +import
> org.apache.directory.server.core.api.authn.ppolicy.PasswordPolicyException;
> >> >>  import org.apache.directory.server.core.api.entry.ClonedServerEntry;
> >> >>  import
> org.apache.directory.server.core.api.interceptor.context.BindOperationContext;
> >> >>  import
> org.apache.directory.server.core.api.interceptor.context.LookupOperationContext;
> >> >> @@ -222,11 +225,27 @@ public class SimpleAuthenticator extends
> >> >>          // Get the stored password, either from cache or from
> backend
> >> >>          byte[][] storedPasswords = principal.getUserPasswords();
> >> >>
> >> >> +        PasswordPolicyException ppe = null;
> >> >> +        try
> >> >> +        {
> >> >> +            checkPwdPolicy( bindContext.getEntry() );
> >> >> +        }
> >> >> +        catch ( PasswordPolicyException e )
> >> >> +        {
> >> >> +            ppe = e;
> >> >> +        }
> >> >> +
> >> >
> >> > the information that checkPwdPolicy() throws is anyway meant to send
> out through the ppolicy response
> >> > control, so there is nothing to prevent here from leaking and it is
> not clear to me why you wait till comparing
> >> > the credentials to throw the exception.
> >> >
> >>
> >> It's not the information inside of the exception that is leaking.  It's
> the fact that a PasswordPolicyException is thrown rather than invalid
> credentials.  This would tell a potential attacker that scans through
> possible names when they have found a valid one.  They could then use that
> information to cause account lockout, or other nefarious things.
> >
> > there is nothing to hide here, cause the ppolicy response control is
> here to send out the status
> > of the account, and this control is created based on the details present
> in this exception.
> >
>
> I understand that the exception would be needed to create a password
> policy control, but I do not think we should be providing that control back
> to an unauthenticated user.  If you are not providing valid credentials,
> should we really provide you with information about the account?
>
> > Note that when a bind request comes with ppolicy request control the
> server must send out a response
> > control with the details like time before expiration, remaining grace
> logins etc.
>
> I follow, but that information only makes sense if the user provided the
> currently valid credentials to start with.  If they don't know the
> password, why would they be provided with the time before password they
> clearly don't know expires?
>
a user/client will never know otherwise whether his login attempt failed
cause the password was
expired.

The servers that implement this ppolicy draft should also need to add
sufficient support to avoid
bruteforce attacks, so I believe that is how the original author made the
trade off.

>>
> >> In general, I don't think we should provide any information other than
> invalid credentials, until the user has successfully authenticated.
> >>
> >> >>          // Now, compare the passwords.
> >> >>          for ( byte[] storedPassword : storedPasswords )
> >> >>          {
> >> >>              if ( PasswordUtil.compareCredentials( credentials,
> storedPassword ) )
> >> >>              {
> >> >> +                if ( ppe != null )
> >> >> +                {
> >> >> +                    LOG.debug( "{} Authentication failed: {}",
> bindContext.getDn(), ppe.getMessage() );
> >> >> +                    throw ppe;
> >> >> +                }
> >> >> +
> >> >>                  if ( IS_DEBUG )
> >> >>                  {
> >> >>                      LOG.debug( "{} Authenticated",
> bindContext.getDn() );
> >> >> @@ -285,7 +304,7 @@ public class SimpleAuthenticator extends
> >> >>              throw e;
> >> >>          }
> >> >>
> >> >> -        checkPwdPolicy( userEntry );
> >> >> +        //checkPwdPolicy( userEntry );
> >> >>
> >> >>          DirectoryService directoryService = getDirectoryService();
> >> >>          String userPasswordAttribute =
> SchemaConstants.USER_PASSWORD_AT;
> >> >>
> >> >> Modified:
> directory/apacheds/trunk/server-integ/src/test/java/org/apache/directory/server/ppolicy/PasswordPolicyIT.java
> >> >> URL:
> http://svn.apache.org/viewvc/directory/apacheds/trunk/server-integ/src/test/java/org/apache/directory/server/ppolicy/PasswordPolicyIT.java?rev=1692562&r1=1692561&r2=1692562&view=diff
> >> >>
> >> >>
> ==============================================================================
> >> >> ---
> directory/apacheds/trunk/server-integ/src/test/java/org/apache/directory/server/ppolicy/PasswordPolicyIT.java
> (original)
> >> >> +++
> directory/apacheds/trunk/server-integ/src/test/java/org/apache/directory/server/ppolicy/PasswordPolicyIT.java
> Fri Jul 24 18:11:38 2015
> >> >> @@ -1131,7 +1131,7 @@ public class PasswordPolicyIT extends Ab
> >> >>          checkBind( userConnection, userDn, "badPassword", 3,
> >> >>              "INVALID_CREDENTIALS: Bind failed: ERR_229 Cannot
> authenticate user cn=userLockout,ou=system" );
> >> >>
> >> >> -        checkBind( userConnection, userDn, "badPassword", 1,
> >> >> +        checkBind( userConnection, userDn, "12345", 1,
> >> >>              "INVALID_CREDENTIALS: Bind failed: account was
> permanently locked" );
> >> >>
> >> >>          userConnection.close();
> >> >>
> >> >>
> >> >
> >> >
> >> >
> >> > --
> >> > Kiran Ayyagari
> >> > http://keydap.com
> >
> >
> >
> >
> > --
> > Kiran Ayyagari
> > http://keydap.com
>



-- 
Kiran Ayyagari
http://keydap.com

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