Forum Discussion
sam_111661
Nimbostratus
Nimbostratusbrute force mitigation
I want to use this irule to authenticate users and allow them only if they have a specific LDAP attribute ldap_attr_value. I would like to know if there is a way to prevent brute force attacks by preventing the username to log in for 15 minutes after 3 authentication failures, many thanks in advance
when HTTP_REQUEST {
set username [HTTP::username]
set password [HTTP::password]
set asid_ldap [AUTH::start pam default_ldap]
AUTH::subscribe $asid_ldap
AUTH::username_credential $asid_ldap $username
AUTH::password_credential $asid_ldap $password
AUTH::authenticate $asid_ldap
HTTP::collect
}
when AUTH_RESULT {
array set auth_response_data [AUTH::response_data]
set ldap_attr [lindex [array get auth_response_data ldap:attr:ldap_attr] 1]
if {[AUTH::status $asid_ldap] == 0 && $ldap_attr equals "ldap_attr_value"} {
HTTP::release
log local0. "ldap_attr is set to: $ldap_attr"
}
else {
HTTP::respond 401
}
}
sam_111661Already figured this out- sam_111661Sure, most of the code is from devcentral so credits go to others and devcentral. This is for mobile activesync access, it does allow access only to activesync (not OWA or so) authenticates the user, checks if he has one of the required attributes in LDAP and allows three authentication failures before it blacklists the user. I have taken the original ldap auth irule and modified it. And yes it is working but the issue I'm having is with authenticating each and every get / post which is not ideal, I'm trying now to add HTTP cookie auth (not sure is supported by mobile activesync) to it but the command HTTP::cookie decrypt is not working for me as it should
when RULE_INIT {
set ::maxauthfail 3
set ::holdtime 300
array set ::blacklist { }
array set ::usertable { }
}
when HTTP_REQUEST {
set srcip [IP::remote_addr]
set currtime [clock second]
if { not ([HTTP::uri] contains "Microsoft-Server-ActiveSync") } {
log local0. "The IP address $srcip is trying to access a non ActiveSync page and has been dropped"
drop
}
if { [ info exists ::blacklist($srcip) ] } {
log local0. "The black list is $::blacklist($srcip)"
if { $::holdtime > [expr ${currtime} - $::blacklist($srcip) ] } {
drop
log local0. "The IP address $srcip is in the blacklist and has been dropped"
return
} else {
unset ::blacklist($srcip)
log "The IP address $srcip has been removed from the blacklist"
}
}
if {not [info exists tmm_auth_http_sids(ldap)]} {
set tmm_auth_sid [AUTH::start pam default_ldap]
set tmm_auth_http_sids(ldap) $tmm_auth_sid
if {[info exists tmm_auth_subscription]} {
AUTH::subscribe $tmm_auth_sid
}
} else {
set tmm_auth_sid $tmm_auth_http_sids(ldap)
}
AUTH::subscribe $tmm_auth_sid
AUTH::username_credential $tmm_auth_sid [HTTP::username]
AUTH::password_credential $tmm_auth_sid [HTTP::password]
AUTH::authenticate $tmm_auth_sid
log local0. "auth. session is: $tmm_auth_sid"
if {not [info exists tmm_auth_http_collect_count]} {
HTTP::collect
set tmm_auth_http_successes 0
set tmm_auth_http_collect_count 1
} else {
incr tmm_auth_http_collect_count
}
}
when AUTH_RESULT {
if {not [info exists tmm_auth_http_sids(ldap)] or \
($tmm_auth_http_sids(ldap) != [AUTH::last_event_session_id]) or \
(not [info exists tmm_auth_http_collect_count])} {
return
}
if {[AUTH::status] == 0} {
incr tmm_auth_http_successes
}
If multiple auth sessions are pending and
one failure results in termination and this is a failure
or enough successes have now occurred
if {([array size tmm_auth_http_sids] > 1) and \
((not [info exists tmm_auth_http_sufficient_successes] or \
($tmm_auth_http_successes >= $tmm_auth_http_sufficient_successes)))} {
Abort the other auth sessions
foreach {type sid} [array get tmm_auth_http_sids] {
unset tmm_auth_http_sids($type)
if {($type ne "ldap") and ($sid != -1)} {
AUTH::abort $sid
incr tmm_auth_http_collect_count -1
}
}
}
array set auth_response_data [AUTH::response_data]
set my_ldap_attr [lindex [array get auth_response_data ldap:attr:my_ldap_attr] 1]
If this is the last outstanding auth then either
release or respond to this session
incr tmm_auth_http_collect_count -1
if {$tmm_auth_http_collect_count == 0} {
unset tmm_auth_http_collect_count
if {[AUTH::status] == 0 && ($my_ldap_attr == "att_value_1" or $my_ldap_attr == "att_value_2")} {
log local0. "my_ldap_attr LDAP attribute is set to: $my_ldap_attr"
HTTP::release
log "logpoint 1a"
set ::usertable(freq,$srcip) 0
log "logpoint 1ab"
log "$srcip^$::usertable(time,$srcip)^$::usertable(freq,$srcip)"
} else {
if { [ info exists ::usertable(time,$srcip)] } {
incr ::usertable(freq,$srcip)
log "$srcip^$::usertable(time,$srcip)^$::usertable(freq,$srcip)"
log "logpoint is 1abc"
if { $::usertable(freq,$srcip) > $::maxauthfail } {
log "new blacklist member <$srcip>"
set ::blacklist($srcip) $currtime
unset ::usertable(freq,$srcip)
unset ::usertable(time,$srcip)
drop
return
} else {
log "logpoint is 1abcd"
HTTP::respond 401
}
} else {
log "logpoint is 1abcde"
HTTP::respond 401
set ::usertable(freq,$srcip) 1
set ::usertable(time,$srcip) $currtime
}
}
}
} - Nice, thanks for sharing!
Colin
