Moodle plugins directory: Anti-hammering / Login blocker | Moodle.org
Anti-hammering / Login blocker
Rogier van DongenSEBSOFT ANTIHAMMER PLUGIN
The Sebsoft Anti Hammering Authentication Plugin offers you the possibility to prevent hammering your login system.
This plugin can be configured to "smart detect" so called hammering on IP basis or for users in general.
Hammering is the process of pretty much brute force attacking Moodle's login system.
This plugin detects the IP address of the remote client, and will track the entered username (and, if the
username exists, also the Moodle userid) and stores it's information to block the user and/or IP address
depending on the configuration of your authentication plugin.
When the plugin has been installed, you should enable or disable blocking by IP and/or username and
configure the timespan at which detection is valid and number of times an attempt can be made.
This plugin can also be configured to make use of the messaging API in moodle.
This is a specific setting that needs to be enabled; if not configured the messaging API will not be used.
Please note receiving messages is not configured for everybody by default. Every applicable person (usually
administrators) MUST configure their preferences if they'd like to receive these messages.
Moodle's lockout system vs Antihammer:
Moodle already has the capability to (temporarily) lock out users https://docs.moodle.org/30/en/Site_policies#Account_lockout)
However, this plugin will add to that functionality, enabling to also take a look at specific IP usage of users trying to login.
There is *no* interaction with the lock out users system of Moodle.
If you want to be able to use the default method of Moodle account locking, but want to use
this plugin for the additional functions of being able to block hammering/testing of passwords
from a certain IP, you need to enable the IP Settings of the antihammer plugin.
You *need* to keep the User mode/setting disabled if you wish to keep Moodle's standard account lockout.
Furthermore this function differs from the Moodle implementation as Moodle will also allow
you to configure if you want to send an e-mail with a unlock link.
The Antihammer authentication method does not do this, as it's more of a way to
provide additional security and possibly block attacks with admin notification.
*Warning*: Whatever you do, do *never* enable both the user mode in Antihammer
AND the account lockout feature together, this may/will cause unintended side effects.
Important note:
This plugin does not neccessarily prevent brute force hacking when IP detection is not configured.
When the only checks are done based on the username, and an attacker uses a different username on virtually
every request (dictionary hacking), a lot of log/status records will be created, but this plugin can't
really do anything (simple because the username is differing too often). In that case IP blocking might help.
Please note this authentication plugin creates administration menu items to view the logs and status tables.
INSTALLATION
- Copy the antihammer folder to your auth directory.
- Configure your authentication plugin.
- We're ready to run!
Useful links
Screenshots
Contributors
If you're a site administrator, you can navigate to "site administration" and there, in the first tab, there should be a navigation option "Anti-hammering / Login blocker" -> "Antihammer reports".
From there you can easily see the users currently blocked and remove their block if really needed.
A new version _will_ be released soon though, as Moodle's message API expects more variables that were previously (quite some time ago) not necessary. Note this does _not_ stand in the way of the workings of the plugin.
Added option to remove all current blocks, modified code according to Moodle expectations (read: resolve notification in debug modus).
Cheers!
This error message me display Argument 4 passed to table_sql::set_sql() must be of the type array, null given, called in /antihammer/classes/table.php on line 223.
Please help me.
@Sa brine: thanks for the report, will be fixed ASAP
New version will likely be available today or after the weekend
Cheers!
Cheers!
Rogier
2. Someone else asked about manually unblocking users, what about IP addresses? Is there a way to manually unblock an IP address?
3. You should consider adding a "repeat offenders" feature similar to the one used in OSSEC. If an offender is blocked they have to wait until they are unblocked. If they commit the same offence within a given time interval, they are blocked for a longer time period; another violation makes the penalty even longer. This way if a legitimate user just screws up their password, they might only have to wait 5 minutes before they can try again (and hopefully not bother calling customer service).
4. We recently had an attack where someone tried using a list of cracked passwords from another site, hoping to find someone that reused their same username and password. They made 30 000 (thirty-thousand) attempts within one hour! They were unsuccessful and our system was able to withstand the burst of traffic. I plan to install Antihammer to defend against any future attempts.
1: maximum attempts basically indicates the maximum number of detected login failures before a temporary account blocking is forced. No other actions are taken into account (this plugin only works in the login scope).
2: From the top of my head: I don't think you can unblock an IP address as such. You can remove single "blocking" records but when a range of users was detected (for example as a result of dictionary/brute force hacking), those can only be removed on a per record basis (although you also have the option to remove all records). Will take this into account for a future release!
3: the repeat offenders feature would be a nice feature indeed. I'll consider it for a future release.
4: Antihammer can be a good line of defense, but please: always take into consideration you may want to tackle this on a different level as well, if possible. These brute force attacks still initiate Moodle "in full". This plugin can do nothing about that because it forces itself in the login process. Therefore the brute force attack could still take your site down.
See changelog for details, most notory changes are the implementation of repeat offenders (must be enabled in global settings first, each time we double up in block duration), removing full IP blocks instead of single block records, IP whitelist (through global settings) and IP lookup (both Moodle's internal iplookup and by opening a new tab to whatismyaddress IP lookup). Support up to Moodle 3.10 has been validated.
Cheers!
Rogier
I just finished installing the new version of Antihammer on my beta system. Thank you for responding so fully to my previous post and for implementing the repeat offenders feature. Of course, I have a few more questions.
My intention is to use the IP blocker mode and not the User mode. With that in consideration I expect that if a bad actor makes repeated, failed attempts to access the system from the same IP address, then the plugin will lock out any further attempts to log into Moodle from that IP address no matter what username they employ. In a case where they make one attempt for user A followed by an attempt for users B, C, D, etc. the source IP address would be blocked. If that is true, then I expect that an attack like I described would be blocked since all of the attempts were made from the same IP address. For a brute force attack to succeed, the bad guys would have to attack from many different IP addresses. Am I wrong?
On another subject, Moodle allows me to rearrange the order that the Authentication plugins are listed. I assume that this means that the methods are applied in the order that they are listed. Therefore, placing Antihammer at the beginning of the list means that blocked IP addresses will be stopped before the other authentication methods are attempted and no time would be wasted trying to process those plugins. Again, please correct me if I’m wrong.
Also, I’m a bit confused by the way that the setting options are presented. For example the first setting is labeled “Block by IP addresses?” followed by an empty check-box and then the words “Default: Yes”. My understanding of a “default” value is that if you don’t alter the setting the default value would be used but since the check-box is empty, does that mean that checking the box will disable IP blocking? More confusion is added when you look at the setting for “Autoclear blocked IPs?” and the Default is also Yes but in this case, after installation the box is already checked! I see this same situation in many other plugins from other developers. Wouldn’t it be clearer if the check-box was replaced by radio buttons labeled yes and no?
Finally, you might consider giving us the option of specifying the time length of the successive penalties for the repeated violations.
Thank you,
Natassia
Please can you confirm whether the latest version is compatible with Moodle V3.11?
Many thanks,
The plugin seems to work as intended up to Moodle 4.0DEV
Cheers