Detection: Potential password in username

Description

The following analytic identifies instances where users may have mistakenly entered their passwords in the username field during authentication attempts. It detects this by analyzing failed authentication events with usernames longer than 7 characters and high Shannon entropy, followed by a successful authentication from the same source to the same destination. This activity is significant as it can indicate potential security risks, such as password exposure. If confirmed malicious, attackers could exploit this to gain unauthorized access, leading to potential data breaches or further compromise of the system.

Search

 1
 2| tstats `security_content_summariesonly` earliest(_time) AS starttime latest(_time) AS endtime latest(sourcetype) AS sourcetype values(Authentication.src) AS src values(Authentication.dest) AS dest count FROM datamodel=Authentication WHERE nodename=Authentication.Failed_Authentication BY "Authentication.user" 
 3| `drop_dm_object_name(Authentication)` 
 4| lookup ut_shannon_lookup word AS user 
 5| where ut_shannon>3 AND len(user)>=8 AND mvcount(src) == 1 
 6| sort count, - ut_shannon 
 7| eval incorrect_cred=user 
 8| eval endtime=endtime+1000 
 9| map maxsearches=70 search="
10| tstats `security_content_summariesonly` earliest(_time) AS starttime latest(_time) AS endtime latest(sourcetype) AS sourcetype values(Authentication.src) AS src values(Authentication.dest) AS dest count FROM datamodel=Authentication WHERE nodename=Authentication.Successful_Authentication Authentication.src=\"$src$\" Authentication.dest=\"$dest$\" sourcetype IN (\"$sourcetype$\") earliest=\"$starttime$\" latest=\"$endtime$\" BY \"Authentication.user\" 
11| `drop_dm_object_name(\"Authentication\")` 
12| `potential_password_in_username_false_positive_reduction` 
13| eval incorrect_cred=\"$incorrect_cred$\" 
14| eval ut_shannon=\"$ut_shannon$\" 
15| sort count" 
16| where user!=incorrect_cred 
17| outlier action=RM count 
18| `potential_password_in_username_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Linux Secure	Linux	'linux_secure'	'/var/log/secure'	N/A

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

To successfully implement this search, you need to have relevant authentication logs mapped to the Authentication data model. You also need to have the Splunk TA URL Toolbox (https://splunkbase.splunk.com/app/2734/) installed. The detection must run with a time interval shorter than endtime+1000.

Known False Positives

Valid usernames with high entropy or source/destination system pairs with multiple authenticating users will make it difficult to identify the real user authenticating.

Associated Analytic Story

• Credential Dumping

• Insider Threat

Risk Based Analytics (RBA)

References

• https://medium.com/@markmotig/search-for-passwords-accidentally-typed-into-the-username-field-975f1a389928

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 2