The Subtle Threat of Usernames with a Trailing Space


In the meticulous arena of cybersecurity, the devil is often in the details. A single character, or even the absence of one, can sometimes be the chink in your armor that adversaries seek. Among such deceptively simple techniques is the creation of a username with a space at the end. A tactic that might seem inconspicuous at first but holds the potential to wreak havoc if overlooked. Let’s delve deep into understanding this, how to test for it, and the associated risks.

Why a Username with a Trailing Space?

Some might wonder, why would anyone create a username with a space at the end? Here are a few reasons:

1. Evading Basic Security Measures: Most basic security scripts or systems might validate for spaces between characters but ignore a trailing space. Such an oversight can be exploited by potential attackers to inject or manipulate data.

2. Misleading Audits & Logs: Security logs or user activity audits might display such usernames without the trailing space, making them appear like their legitimate counterparts. This can conceal malicious activity.

Following examples of misleading users:

1. Two Administrators accounts? 
2. Local users with the names Network Service and System ?

To identify and investigating an incident with those users, become almost impossible.

Testing Your SOC for Trailing Spaces:

1. Create the User: (Using Administrator privilege)


					New-LocalUser -Name "Administrator " -NoPassword
New-LocalUser -Name "STSTEM " -NoPassword
New-LocalUser -Name "NETWORK SERVICE " -NoPassword


2. Login Attempt: Try to log in using this new username.

    You will need to reset the password before.
3. Audit Check: Review your security logs. Does the system record the login attempt          accurately, with the trailing space? Or does it overlook or trim the space, confusing it      with any other legitimate username?
4. Alert Mechanism: Does your SOC send out an alert for this unusual activity? A              sophisticated Security Operations Center should flag such nuances as potential                threats.

Potential Risks:

1. Impersonation: Attackers can create a username that appears almost identical to a


    legitimate one, save for the trailing space. Unsuspecting users or admins might then

    assign this user unintended permissions.

2. Data Integrity: If systems fail to differentiate between a username with a trailing


    space and its legitimate counterpart, data integrity can be compromised. Two different

    users might inadvertently be treated as one.

3. System Vulnerabilities: Certain systems or applications might become erratic or


    unstable when faced with unexpected inputs, like a username with a trailing space.

4. Compromised Audits: If your SOC doesn’t recognize or flag such users, your audit


    logs can become unreliable. Attackers can hide their activities under the guise of these

    deceptive usernames.

In Conclusion:

As we strengthen our cybersecurity infrastructures, attackers continue to evolve, often resorting to subtleties that might go unnoticed. While a username with a trailing space might seem trivial, its potential threats underscore the need for robust, sophisticated, and meticulous Security Operations Centers. Your SOC must not only defend against glaring threats but also identify the silent, lurking ones. After all, in cybersecurity, every space—leading, middle, or trailing—counts.


For our customers at CyRay, this potential vulnerability isn’t a blind spot. From the inception – that is, the very creation of such a user – our systems are tuned to detect and alert. Whether the user was fashioned with that trailing space recently or was a relic from before our monitoring commenced, our mechanisms ensure that no such nuances slide under the radar.

But our vigilance doesn’t halt here. We’re not just talking about spaces. Be it non-characters at the end, unusual patterns, or any other deviations from the norm, CyRay is equipped to recognize and combat a wide spectrum of sophisticated attack scenarios. By aligning with CyRay, you’re not just implementing a security solution; you’re adopting an ever-evolving shield, ensuring that both the obvious and the covert threats are kept at bay. Rest assured, with CyRay, every detail counts.

Stay Ahead with CyRay’s Newsletter:

Want to ensure you’re always a step ahead in the cybersecurity game?
Sign up to our newsletter! => Click Here.
With it, we bring the ‘Test Your SOC’ use cases directly to your inbox, ensuring you’re armed with the latest insights and strategies to safeguard your digital landscape.

Coming Soon:

Dive deep into the mysterious world of digital apparitions with our upcoming feature: “Creating A Ghost User 👻 – A User That Can’t Be Seen!” You won’t want to miss this intriguing exploration into invisible user profiles and the potential security ramifications they pose. Stay tuned!

More to explorer

New Deployed Rules

Process CreationSuspicious Execution Location Of Wermgr.EXEPotential CVE-2023-36874 Exploitation – Fake Wermgr ExecutionNetwork Reconnaissance ActivityNode Process ExecutionsNslookup PowerShell Download Cradle – Process CreationSuspicious

New Deployed Rules

Account ManagementOutgoing Logon with New CredentialsRottenPotato Like Attack PatternScanner PoC for CVE-2019-0708 RDP RCE Vuln File EventWebDAV Temporary Local File CreationSCR File

New Deployed Rules

Process CreationMMC20 Lateral Movement Process CreationMMC Spawning Windows Shell Process CreationPotential Arbitrary Command Execution Using Msdt.EXE Process CreationSuspicious MSDT Parent Process Process

Sign up for our newsletter

Time to market

One-day SIEM integration