I think your idea seems equally reasonable. I considered something similar.
However, we’re using SMS as the 2nd factor, which is imperfect from a security
point of view but much better from a distribution and usability point of view.
I’m guessing you have some sort of token generator for the 2nd factor. The key
point being that there’s a difference in workflow:
User supplies username + password -> System sends token to user
-> User inputs token
vs.
User generates token -> User supplies username, password and
token
Richard
From: Björn Raupach [mailto:[email protected]]
Sent: Sunday, January 8, 2017 12:02 PM
To: [email protected]
Subject: Re: MFA - Possible Solution?
Hi Richard,
I am currently working on an implementation for U2F with Apache Shiro. It is
still not officially
rolled out but it works and I am also not sure if I did it correct.
Like you I created two realms. Then however I changed the authentication
strategy in the
security manager.
authcStrategy = org.apache.shiro.authc.pam.AllSuccessfulStrategy
securityManager.authenticator.authenticationStrategy = $authcStrategy
securityManager.realms = $jdbcRealm, $u2fRealm
I used U2FAuthenticationToken that extends UsernamePasswordToken
that works on both realms. The custom U2FRealm overrides supports and checks
that the token
is an instance of U2FAuthenticationToken.
On 6 Jan 2017, at 19:27, Richard Wheeldon
<[email protected]<mailto:[email protected]>> wrote:
Hi,
As a few of you may know, I posted many, many months ago about trying to get
Multi Factor Authentication working on a Shiro-based app. I think I have a plan
that isn’t totally crazy and doesn’t involve stupid levels of custom code or
changing any of the core Shiro libs. However, I’d like it run it by you guys to
see what you think and poke holes in it before I turn it into prod-ready code.
Maybe there’s something here that folks can adapt in the future if they need to
do something similar.
I started off with a pre-existing config with a DefaultWebSessionManager and a
JDBC realm reading username / password and role info from a PG DB. Apart from a
non-standard session manager and a non-standard cookie name, it’s fairly
bog-standard stuff.
What I’m doing now is to split the JDBC logic into two realms. The first is the
same password stuff:
passwordJdbcRealm = org.apache.shiro.realm.jdbc.JdbcRealm
passwordJdbcRealm.permissionsLookupEnabled = true
passwordJdbcRealm.authenticationQuery = select password from users where …
passwordJdbcRealm.userRolesQuery = select …
passwordJdbcRealm.dataSource = $dataSource
passwordJdbcRealm.credentialsMatcher = $passwordMatcher
passwordJdbcRealm.permissionsQuery = select …
The second is for accessing one-time authentication tokens:
tokenJdbcRealm = org.apache.shiro.realm.jdbc.JdbcRealm
tokenJdbcRealm.permissionsLookupEnabled = false
tokenJdbcRealm.authenticationQuery = select token from auth_tokens where …
tokenJdbcRealm.userRolesQuery = select null where ? is not null and false (must
be a neater way just to disable role lookups but this works)
tokenJdbcRealm.dataSource = $dataSource
tokenJdbcRealm.credentialsMatcher = $tokenMatcher
Both of these are now bound to the same old security manager:
securityManager.realms = $passwordJdbcRealm, $tokenJdbcRealm
I’ve now also got two form filters - one for the password and a new one for the
one-time token:
passwordFormAuth =com.voxsmart.PasswordFormAuthenticationFilter
passwordFormAuth.loginUrl = /login.jsp
tokenFormAuth = com.voxsmart….TokenFormAuthenticationFilter
tokenFormAuth.loginUrl = /login2.jsp
login2.jsp redirects to login.jsp if the user isn’t authenticated.
These form filters are wired up like so:
/login.jsp = passwordFormAuth
/login2.jsp = tokenFormAuth
/logout = logout
/** = tokenFormAuth
The first is basic except for sending out a token if the login succeeds:
@Override
public boolean onLoginSuccess(AuthenticationToken token, Subject subject,
ServletRequest request, ServletResponse response) throws Exception {
// Generate a one-time token, write it to the
DB and send it to the user via SMS / e-mail / carrier pigeon
}
The second checks that an MFA attribute is set on the session in order to allow
access and sets it if / only if the token match is found:
private boolean isMfaOk(Object mfaStatus) {
return "ALLOWED".equals(mfaStatus) ||
"NOT_NEEDED".equals(mfaStatus);
}
@Override
public boolean isAccessAllowed(ServletRequest request, ServletResponse
response, Object mappedValue) {
Object mfaStatus = subject.getSession().getAttribute("MFA-STATUS");
return (subject.isAuthenticated() && isMfaOk(mfaStatus)) || // Additional check
for MFA
(!isLoginRequest(request, response) && isPermissive(mappedValue)); //
Copy-n-paste from AuthenticatingFilter
}
@Override
public boolean onLoginSuccess(AuthenticationToken token,
Subject subject, ServletRequest request, ServletResponse response) throws
Exception {
boolean ret = super.onLoginSuccess(token, subject, request, response);
subject.getSession().setAttribute("MFA-STATUS", "ALLOWED");
// write some audit log entries and other fluff
return ret;
}
Does this seem sane? Is there a better way to do it? Is there something I’m
missing or forgotten that will cause this to blow up in my face at some later
point in time? Is there something that could be cribbed and added to Shiro to
make it easier in the future?
Regards,
Richard
