Uncovering Hidden Users: A Guide to Finding Service Accounts on Servers

Service accounts are often overlooked users on servers and workstations that can pose serious risks if not properly managed and secured. As organizations focus on strengthening human user account security, service accounts are frequently left unmonitored. This grants broad access and privileges that can be compromised by malicious actors. Monitoring service accounts and understanding their permissions is crucial to establishing a strong security posture.

This article provides a comprehensive guide to identifying service accounts across an environment. It outlines common account types, locations, and discovery methods to build a full inventory of service accounts. It also highlights how a dedicated solution like Silverfort can automate the discovery, access control and protection of all service accounts in the environment, providing organizations with granular visibility into every non-human identity and machine-to-machine authentication, as well as its sources, destinations, authentication protocols, and activity volume.

By gaining visibility and control over service accounts, organizations can close a critical security gap and strengthen their overall identity and access management programs.

What are Service Accounts

Service accounts are machine-to-machine user accounts used by applications and services to access resources and perform automated tasks. Often service accounts have elevated privileges which makes them prime targets for attackers. To properly secure service accounts, organizations first need to locate them on their servers.

The most effective way to locate service accounts at scale is to use a solution like Silverfort that can automatically discover domain user accounts, determine which ones are service accounts, monitor them for anomalies, and protect them from identity-based attacks. By gaining comprehensive visibility into service accounts, organizations can harden security and simplify compliance.

Why You Need to Find Service Accounts

Service accounts are a necessity for many server operations, but they also pose security risks if not properly managed. To strengthen security and compliance, organizations need to discover and monitor all service accounts on their servers.

Service accounts are operating system accounts used by applications, services or scripts to interact with the system. They allow automated processes to run without human intervention. However, because service accounts often have privileged access, they are attractive targets for attackers. If compromised, they can be used to gain full control of servers and access sensitive data.

Common Types of Service Accounts

Service accounts are a type of user account created specifically for non-human access to IT systems and services. They are commonly used by applications, scripts, and automation tools to access resources and perform actions. There are several common types of service accounts found on servers:

Local Service Accounts

Local service accounts run system services on individual devices. They are created and managed locally and not shared across systems.

Network Service Accounts

Network service accounts provide a consistent identity for services to access resources across networks. They have a broader scope than local service accounts and can be used by multiple systems within a network.

Managed Service Accounts (MSAs)

Managed service accounts are Active Directory accounts that automate password management, simplify administration, and improve security. They’re tied to a service, not an individual administrator, and can be used by multiple systems in a domain.

Hybrid Service Accounts

Hybrid service accounts are designed to operate across both on-premises and cloud environments. These accounts bridge the gap between traditional network boundaries and cloud-based resources, making them essential in modern, hybrid IT infrastructures. They often require careful configuration to ensure secure and seamless access across different platforms. Hybrid service accounts are particularly relevant for organizations transitioning to the cloud or operating in a mixed environment, where they need to interact with both local data centers and cloud services like AWS, Azure, or Google Cloud.

Scanners

Scanner service accounts are used by automated tools that perform network or security scans. These accounts require specific permissions to scan systems, networks, and applications for vulnerabilities or compliance checks. Unlike traditional service accounts, scanner accounts often have elevated privileges to access various network segments and systems, making them a critical component of cybersecurity strategies. However, due to their elevated access, they must be tightly controlled and monitored to prevent misuse or exploitation.

Locating Service Accounts in Windows

Locating service accounts on Windows servers requires investigating several areas of the system. Service accounts are non-interactive user accounts used by Windows services and applications to access resources. 

To find service accounts on Windows servers, start by examining the Services console. This contains a list of all installed services, including the accounts they use. Look for accounts with names like “Local Service,” “Network Service,” or “[Service Name] Service Account.” Note that some services use the SYSTEM account, which has full control of the system.

Next, check for scheduled tasks by going to Task Scheduler > Task Scheduler Library. Here you’ll find tasks that automatically run on a schedule, and the accounts used to run them. Look for any tasks running under privileged service accounts.

Then review the Event Viewer, which logs events from Windows services and applications. Go to Windows Logs > Security and look for events with a Logon Type of “Service.” The Account Name field will show the service account used. This can uncover service accounts not listed in the Services console or Task Scheduler.

It’s also important to check for service accounts in the registry. Go to HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows NT\Service Profiles and look for subkeys named after service accounts. These contain runtime configurations for services using those accounts.

Finally, use a tool like the Sysinternals Autoruns utility to scan for Windows Autostart locations. This finds program shortcuts, registry entries, and file system locations where applications run at startup. Review the entries to see if any services are configured to start automatically using privileged service accounts.

By thoroughly investigating these areas of a Windows server, organizations can locate hidden service accounts and ensure they are properly secured and monitored. Using a solution like Silverfort’s agentless platform is the best way to automatically discover, assess and protect all service accounts across an environment.

Locating Service Accounts in Linux

Locating service accounts on Linux servers requires careful detection methods. These privileged accounts are often hidden or disguised to avoid detection, so standard user account discovery techniques may miss them.

To uncover service accounts on Linux systems, security professionals should:

Check for accounts with UID below 1000

On Linux, UID values below 1000 are typically reserved for system accounts. Any accounts with a UID under 1000 should be investigated to determine if they are service accounts. These may include accounts like “nobody,” “dbus,” or “apache.”

Analyze account naming conventions

Service accounts frequently follow standard naming conventions, like “svc-,” “service-,” or “daemon-.” Accounts following these patterns may be service accounts and should be verified. Some common examples are “svc-admin,” “service-app,” or “daemon-data.”

Review account login shells

Service accounts typically have restricted login shells, like “/sbin/nologin” or “/bin/false.” Any account with one of these as the login shell is likely a service account. This can be checked by running grep /sbin/nologin /etc/passwd or a similar command.

Check account home directories

Service accounts often have home directories set to “/dev/null” or “/.” If an account has one of these as the home directory, it is probably a service account. This can be detected using grep ‘/dev/null’ /etc/passwd or grep ‘/’ /etc/passwd.

Monitor account login events

Because service accounts are typically non-interactive accounts, there should be no login events for these accounts. Any account without login events over a period of time is potentially a service account. This can be checked by analyzing the /var/log/secure or /var/log/auth.log login logs.

Using these detection methods, security teams can uncover hidden and disguised service accounts on Linux systems. With a solution like Silverfort, these accounts can then be monitored and protected to help close security gaps and reduce risks.

Locating Service Accounts in Active Directory

Discovering service accounts in Active Directory can be a challenging task that requires a meticulous approach. These accounts often remain hidden or camouflaged to avoid detection, making it crucial to employ effective techniques specifically designed for their discovery.

To uncover service accounts within an Active Directory environment, security professionals should consider the following strategies:

Analyze account naming conventions

Service accounts in Active Directory frequently adhere to naming conventions that distinguish them from regular user accounts. Look for accounts with names following patterns such as “svc-,” “service-,” or “daemon-.” Examples may include “svc-admin,” “service-app,” or “daemon-data.” Identifying these naming patterns can significantly aid in locating potential service accounts.

Review account properties and attributes

Within Active Directory, service accounts often possess distinctive properties that set them apart. Examine attributes like the servicePrincipalName and description to identify accounts specifically designed for system or application services. Additionally, consider investigating the account membership in privileged groups like Administrators or Domain Admins.

Monitor account activity and usage

Since service accounts are typically non-interactive, monitoring their activity can help identify potential candidates. Analyze event logs and audit trails to detect accounts with no or minimal login events over a given period. Tools like Windows Event Viewer or specialized security solutions can assist in tracking account login events effectively.

Check for special account flags

Active Directory provides specific account flags that indicate the purpose or nature of an account. Flags such as DONT_EXPIRE_PASSWORD, SMARTCARD_REQUIRED, or TRUSTED_FOR_DELEGATION can signal service accounts. Identifying these flags can narrow down the search for hidden service accounts.

By employing these detection techniques, security teams can successfully uncover concealed service accounts within an Active Directory environment. Once identified, these accounts can be closely monitored and safeguarded using solutions like Silverfort, bolstering overall security and minimizing potential risks.

Continuing to prioritize the identification and protection of service accounts ensures comprehensive security measures are in place, enhancing the resilience of Active Directory infrastructures and safeguarding critical assets.

Remember, constant vigilance and proactive measures are key when it comes to securing Active Directory against hidden service accounts.

Spotting Suspicious Service Accounts

Suspicious service accounts are user accounts that have been created to provide access to applications and services, rather than individual users. However, malicious actors often create service accounts to hide their activity and maintain persistence.

Some signs that a service account may have been compromised include:

• The account has an overabundance of privileges. Legitimate service accounts typically only have the minimum permissions required to function. Excessive privileges could indicate the account has been hijacked.
• The account is not documented. Most organizations maintain records of authorized service accounts and their purposes. Undocumented accounts are more difficult to monitor and are attractive targets for compromise.
• The account is inactive for long periods of time. Authentic service accounts are typically active and show regular logins, file access, etc. Dormant accounts that suddenly become active could signal unauthorized access.
• The account has an illogical naming convention. Legitimate service accounts usually follow a standard naming format to indicate their purpose. Illogical or misleading account names may have been selected to avoid detection.
• Login times are unusual. Most service accounts have predictable login schedules related to their functions. Irregular login times, especially during off hours, could indicate the account has been compromised.
• Multiple failed login attempts. Repeated failed logins could show that someone is attempting to guess the account’s password through brute force. This behavior warrants investigation, as a successful compromise may have occurred or may be imminent.
• Links to malicious files or connections. If a service account is associated with known malware files, command and control servers, or other indicators of compromise, it is likely that the account has been hijacked for malicious purposes.

By closely monitoring service accounts for these suspicious signs and employing a tool like Silverfort to discover and manage accounts, organizations can detect compromises early and remediate risks before major damage occurs. Constant surveillance is key to identifying and mitigating threats from malicious service accounts.

Best Practices for Managing Service Accounts

To properly manage service accounts, several best practices should be followed. These help reduce risk and ensure service accounts have the least privileged access.

The first best practice is to regularly review service accounts and disable or remove any that are no longer needed. Service accounts that are no longer used can be prime targets for attackers and should be removed to reduce the attack surface.

Another best practice is to use unique passwords for each service account. Reusing the same password across multiple accounts allows attackers to easily access more systems if one account is compromised. Using a password manager can help generate and store unique, complex passwords for each service account.

Enable multi-factor authentication (MFA) on service accounts whenever possible. MFA adds an extra layer of security for accessing accounts by requiring not just a password but also a code sent to a mobile device or a biometric like a fingerprint. With MFA enabled attackers would need to compromise both the password and the mobile device to access the account.

Tightly control the permissions and privileges for each service account. Service accounts should only have the minimum permissions needed to perform their specific functions. Periodically review account permissions and remove any that are unnecessary. Less privileged accounts are less valuable targets for attackers.

Monitor service accounts for signs of compromise or misuse. Monitor account login times, locations, and frequencies to detect anomalous behavior that could indicate an account has been compromised. Also monitor file access, account lockouts, and privilege escalation to detect potentially malicious activity. Quickly responding to detected issues can help prevent or limit damage from attacks.

Following these best practices for managing service accounts helps reduce risks, improves security, and ensures service accounts have the least privilege access as recommended by experts like Silverfort. Strict management and control of service accounts are key to avoiding breaches and protecting infrastructure.

How Silverfort Discovers Service Accounts Automatically

Silverfort automatically discovers service accounts on servers using a combination of machine learning, behavioral analysis, and credential access analytics. Rather than relying on static lists of known service accounts, Silverfort dynamically detects accounts exhibiting service account behavior.

Behavioral Detection

Silverfort analyzes account login times, source IP addresses, and commands run to identify patterns indicating automated service account usage versus interactive human access. Machine learning algorithms establish a behavioral baseline and then detect anomalies that signify a service account. For example, an account that runs the same commands at the exact same time every day is likely a service account.

Access Monitoring

By monitoring which accounts access privileged credentials like administrator passwords, API keys, and database logins, Silverfort can infer service account usage. Legitimate service accounts will repeatedly access the same credentials according to their automated schedules. In contrast, human users tend to access a wider range and do so more sporadically.

Machine Learning

Silverfort’s machine learning models analyze huge volumes of data to determine the probability of any given account being a service account based on its attributes and behaviors. The models get smarter over time as they are exposed to more servers and accounts. They can detect even subtle patterns that would be nearly impossible for humans to discern. Machine learning allows Silverfort to achieve a high degree of accuracy with a low rate of false positives.

Continuous Monitoring

Whereas manual identification of service accounts provides only a point-in-time snapshot, Silverfort monitors accounts continuously to detect new service accounts as soon as they become active. Continuous monitoring also alerts to changes in service account behavior that could indicate compromised credentials or account takeover attempts by malicious actors. By automatically discovering service accounts, Silverfort gives security teams comprehensive visibility into this vulnerable area of the IT environment.

Silverfort employs machine learning algorithms that establish a baseline of normal behavior for each service account. Deviations from expected patterns trigger alerts, allowing security teams to investigate and respond quickly. The platform monitors parameters like:

• Login locations – Detects logins from new geographical locations or devices not previously used by the account.
• Login times – Flags logins outside of normal business hours or at times when the account is typically inactive.
• Commands and activities – Identifies unusual commands, scripts or other behaviors that could indicate malicious activity.
• Resource access – Monitors changes in resources, files, directories or systems accessed by the service account.
• Configuration changes – Detects modifications to account settings, permissions, ownership or other properties that could weaken security controls.

Silverfort’s agentless approach means no software needs to be installed on servers or devices. The solution integrates with existing directory services like Active Directory to import service account details. It uses machine learning to establish a baseline and then continuously monitors for anomalies that may represent threats.

When the system detects abnormal service account activity, it generates an alert with details about the event. Security teams can then lock down the account to prevent further access, check account logs to determine the scope of unauthorized use, and remediate issues to restore security.

Continuous monitoring of service accounts is key to reducing risks from compromised credentials or insider threats. By establishing normal behavior patterns and detecting meaningful deviations, Silverfort provides unparalleled visibility and control over service accounts, helping organizations strengthen security postures and simplify compliance.

Conclusion

While service accounts are essential to the functioning of enterprise systems, they are often overlooked and poorly managed. This leaves organizations vulnerable to attacks targeting these privileged accounts. As this guide has shown, there are several methods to uncover service accounts on servers, but the most effective approach is to deploy a dedicated solution like Silverfort.

Our agentless platform can scan servers to discover all service accounts, monitor them for anomalies, and enforce least privilege policies to lock down access. For any organization serious about cyber risk reduction and compliance, a solution focused on service account security should be an absolute priority. With the right tools and strategies in place, service accounts can be secured and managed properly.