For many organizations, Active Directory (AD) service accounts are quiet afterthoughts, sticking to the background much after the original purpose was forgotten. Worse, these orphaned service accounts (created for legacy applications, scheduled tasks, automation scripts, or test environments) often remain active with unofficial or old passwords.
It’s not surprising that advertising service accounts frequently circumvent daily security surveillance. Overwhelmed by daily demands and prolonged technical debt, security teams can often overlook service accounts (not linked to individual users and rarely scrutinized) and quietly disappear into the background. However, this obscurity becomes a major target for attackers looking for stealthy ways to the network. And unforgettable service accounts can act as silent gateways for attack routes and lateral movements across the enterprise environment. In this article, we will explore the risk of forgotten ad service accounts posing and how to reduce exposure.
Reveal and stock what has been forgotten
As the old cybersecurity adage progresses, we cannot protect what is invisible. This is especially true for advertising service accounts. Gaining visibility is the first step to protecting them, but orphans or unsupervised service accounts often work quietly in the background, avoiding notifications and surveillance. These forgotten service accounts are particularly problematic as they have played a central role in some of the most harmful breaches in recent years. In the case of the 2020 SolarWinds attack, the compromised service accounts helped threat actors navigate the target environment and access sensitive systems.
Once an attacker gains foothold through phishing or social engineering, the next move typically leverages and uses service accounts to increase privileges and hunts for service accounts to move sideways through the network. Fortunately, administrators have a variety of techniques that can be used to identify and reveal forgotten advertising service accounts.
Query AD for Service Principal Name (SPN)-enabled accounts. This is usually used by services to authenticate with other systems. Filter accounts with incorrect passwords or have not been logged in for a long time. Scans scheduled tasks and scripts for hardcoding or built-in credentials that reference unused accounts. Review group membership abnormalities. The service account may be inheriting privileges that have risen over time. Audit Active Directory. Specops’ Free Ad Audit Tool: You can perform read-only scans using Specops password auditor
Real World Example: Botnets Abuse Forgotten Accounts
In early 2024, security researchers discovered botnets of over 130,000 devices targeting Microsoft 365 service accounts in a massive password spray campaign. The attacker bypassed Multifactor Authentication (MFA) by abusing basic authentication. These attacks did not trigger typical security alerts, so many organizations didn’t realize they had compromised. This example is just one of many that emphasizes the importance of securing service accounts and eliminating legacy authentication mechanisms.
Privilege creep leads to quiet escalation
Even service accounts initially created with minimal privileges can become dangerous over time. This scenario, known as privileged creep, occurs when an account accumulates permissions through system upgrades, role changes, or nested group memberships. What starts as a low-risk utility account can quietly evolve into a high-impact threat that allows you to access critical systems without anyone realizing it.
Therefore, security teams should periodically check the role and permissions of service accounts. If access is not actively managed, even well-intentioned compositions can drift into dangerous territory.
Important practices to protect your advertising service account
Effective advertising service account management requires a deliberate and disciplined approach as these logins are valuable targets that require proper handling. Below are some best practices that form the backbone of a powerful advertising service account security strategy:
Enforce minimal privileges
Grant only the permissions absolutely necessary for each account to function. Do not place service accounts in a wide range of groups, such as domain administrators.
Use a managed service account and a group managed service account
Managed Service Accounts (MSAs) and Group Managed Service Accounts (GMSAs) provide automatic password rotation and cannot be used for interactive log-ins. This makes it safer and easier to maintain than traditional user accounts.
Periodic audits
Use built-in ad auditing or third-party tools to track account usage, login and permission changes. Beware of signs of misuse or misunderstanding.
We implement strong password policies
Long and complex passphrases must be the standard. Avoid reused or hardcoded credentials. Passwords must be rotated periodically or managed via automated tools.
Limit usage
Service accounts must not allow interactive log-ins. Assign a unique account to each service or application to contain potential compromises.
Actively disable unused accounts
If your account is no longer in use, you must disable it immediately. Regular PowerShell queries can help you identify old or inactive accounts.
Individual roles
Create separate service accounts for various functions, including application services, database access, and network tasks. This compartmentation reduces the impact radius of one compromise.
Apply MFA if necessary
Service accounts must not support interactive log-ins, but some instances may require exceptions. For these edge cases, MFA can increase security.
Use a dedicated organizational unit
Grouping service accounts in a specific organizational unit (OUS) simplifies policy enforcement and auditing. It also helps to spot anomalies and maintain consistency.
Check dependencies and access
As your environment evolves, we will reconsider whether you need the same level of access as each service account is used. Adjust or deprecate your account accordingly.
Automation and tools streamline the security of your advertising service accounts
The SPECOPS Password Auditor performs a read-only scan of Active Directory to identify weak passwords, unused accounts, and other vulnerabilities without changing your ad settings. Built-in reports and alerts allow security teams to proactively address the risks of their advertising service accounts, instead of waiting for a violation to occur. Password management, policy enforcement, and audit automation provide greater security and reduces management overhead. Download it for free.
Finding problems is one thing, but you need to focus on prevention. Manually implementing other best practices listed in this article is not a small feat. Fortunately, tools like Specops Password Policy can help you automate many of these processes and implement these best practices in a manageable and scalable way across your active directory environment. Book a demo of Specops Password Policy now.
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