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Cybersecurity · head to head

Semperis vs Tenable Nessus

Semperis logo

Semperis

Cybersecurity

Identity threat detection and Active Directory forest recovery for AD, Entra ID and Okta, from a privately held US vendor.

From
On request
Rated
-
Full reviewWebsite
Tenable Nessus logo

Tenable Nessus

Cybersecurity

Network vulnerability scanner

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only Tenable Nessus has a free tier, so it costs nothing to try first.
  • Each has a real cost: Semperis scope is limited to Active Directory, Entra ID and Okta, so an organisation whose critical identity lives elsewhere gets little from it, and the recovery value declines in direct proportion to how much has already moved off on-premises AD.; Tenable Nessus nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
  • They diverge on capability: Semperis covers Active Directory Forest Recovery, Tenable Nessus covers Network scanning.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Semperis and Tenable Nessus actually diverge.

Attributes where Semperis and Tenable Nessus differ
AttributeSemperisTenable Nessus
Starting priceOn requestFree
Pricing modelquotesubscription
Free tierNoYes
PlatformsWebWindows, Linux, Macos, Cloud
FoundedUnknown2002

Identical on both: user rating (Not yet rated), category (Cybersecurity).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Semperis

  • Active Directory Forest Recovery
  • Malware-free restore
  • Replication-stream monitoring
  • Automated rollback
  • Attack indicator scoring
  • Entra ID and Okta coverage
  • Purple Knight
  • Forest Druid

Only in Tenable Nessus

  • Network scanning
  • Vulnerability detection
  • Configuration assessment
  • Malware detection
  • Compliance checking
  • Cloud security assessment
  • Mobile scanning
  • API access

What people use each for

The jobs each tool is most often brought in to do.

Semperis

  • An organisation that cannot answer an auditor or insurer asking how long it would take to rebuild Active Directory after a destructive attacknot Tenable Nessus
  • Post-incident recovery where domain controllers are compromised and restoring from system-state backup would reintroduce the attacker's footholdnot Tenable Nessus
  • Continuous detection of privileged group changes and directory-level tampering that domain controller security logs missnot Tenable Nessus
  • Hybrid estates where AD, Entra ID and Okta all matter and no single tool currently shows changes across the threenot Tenable Nessus

Tenable Nessus

  • Vulnerability scanning of servers, network devices and web applicationsnot Semperis
  • Configuration and compliance auditing against hardening benchmarksnot Semperis
  • Point in time assessments by consultants and penetration testersnot Semperis

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Semperis

  • Scope is limited to Active Directory, Entra ID and Okta, so an organisation whose critical identity lives elsewhere gets little from it, and the recovery value declines in direct proportion to how much has already moved off on-premises AD.
  • The licence buys tooling, not a proven runbook: forest recovery is only worth what your last rehearsal demonstrated, and a plan that has never been executed end to end in a lab is an untested assumption regardless of what was purchased.
  • It overlaps with backup and directory management products from Quest, Veeam, Commvault and others, so the buyer must argue internally why a dedicated product is needed alongside a backup contract that already claims to protect Active Directory.
  • Running Directory Services Protector well requires someone who understands AD internals, replication metadata and Tier 0 attack paths, and without that person the alerts on privileged changes are either ignored or auto-reverted in ways that break legitimate administration.
  • Licensing is driven by identity object counts, so directories carrying years of stale user accounts and service principals pay for objects that should have been deleted, and the cleanup project that would reduce the bill is the one nobody has time for.

Tenable Nessus

  • Nessus Professional is $4,790 for one year, sold as an annual licence rather than a per scan or usage based fee
  • Support beyond the base entitlement costs an extra $400 per year for Advanced Support with 24x365 phone and chat access
  • The on demand training course is a separate $275 purchase for a single person for one year
  • Multi year discounts require paying for two or three years up front

Pricing, plan by plan

Semperis

On request

No published plan breakdown. See the Semperis review.

Tenable Nessus

Free
  • Nessus EssentialsFree
    • Up to 16 ips
    • Network scanning
    • Vulnerability assessment
  • Nessus Professional$2600/year
    • Unlimited targets
    • Enterprise features
    • Advanced analytics
  • Nessus Expert$5200/year
    • All Professional features
    • Cloud integration
    • Advanced reporting

Which should you pick?

Choose Semperis if

  • You need active directory forest recovery.
  • You also want malware-free restore.
Semperis review

Choose Tenable Nessus if

  • You need network scanning.
  • You want to start without paying.
  • You work on Windows, Linux, Macos, Cloud.
  • You also want vulnerability detection.
Tenable Nessus review

Questions people ask

Is Semperis or Tenable Nessus better?
Neither clearly leads. Semperis starts at On request and Tenable Nessus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Semperis or Tenable Nessus?
Tenable Nessus has a free tier; the other does not. Paid plans start at On request for Semperis and Free for Tenable Nessus.
Does Semperis or Tenable Nessus run on more platforms?
Semperis runs on Web. Tenable Nessus runs on Windows, Linux, Macos, Cloud.
Can I use Tenable Nessus for free?
Yes. Tenable Nessus has a free tier, so you can try it without paying. Semperis starts at On request.
What is Semperis best used for?
Semperis is most often used for an organisation that cannot answer an auditor or insurer asking how long it would take to rebuild active directory after a destructive attack, post-incident recovery where domain controllers are compromised and restoring from system-state backup would reintroduce the attacker's foothold, continuous detection of privileged group changes and directory-level tampering that domain controller security logs miss, hybrid estates where ad, entra id and okta all matter and no single tool currently shows changes across the three. Of those, an organisation that cannot answer an auditor or insurer asking how long it would take to rebuild active directory after a destructive attack and post-incident recovery where domain controllers are compromised and restoring from system-state backup would reintroduce the attacker's foothold are not what Tenable Nessus is typically brought in for.
What can Semperis do that Tenable Nessus cannot?
Semperis covers Active Directory Forest Recovery, Malware-free restore, Replication-stream monitoring, Automated rollback. Tenable Nessus covers Network scanning, Vulnerability detection, Configuration assessment, Malware detection.

Answered from the vendors’ own pages

Semperis: Does this replace my backups?

No. It replaces the Active Directory recovery procedure specifically. You still need backups for everything else, and the point of Semperis is that a generic system-state backup of a domain controller is a poor way to recover a forest because it restores the operating system along with whatever compromised it.

Tenable Nessus: What are the three Nessus offerings?

Nessus Essentials is a free introductory offering for educators, students, and career starters, limited to 16 IPs for scanning. Nessus Professional is designed for consultants and SMBs, providing unlimited IT scans across any location. Nessus Expert is the premium offering extending Professional with web application scanning, infrastructure-as-code scanning, and external attack surface assessment up to 5 domains.

Source
Semperis: Is it useful if we are cloud-only on Entra ID?

Partly. Directory Services Protector covers Entra ID and Okta for change tracking and posture, but the forest recovery product, which is the strongest reason to buy, applies to on-premises Active Directory. A genuinely cloud-only organisation should weigh it against Microsoft's own tooling.

Tenable Nessus: What OS platforms does Nessus support?

Nessus runs on Debian/Kali Linux, Fedora, FreeBSD, Mac OS X, Red Hat/CentOS, SUSE Linux, Ubuntu, and various Windows versions including Server 2008, 2012, and Windows 7-10.

Source
Semperis: Are Purple Knight and Forest Druid really free?

Yes, both are free downloads with no licence requirement, and they are widely used by organisations that are not Semperis customers. They are also, transparently, the top of the sales funnel.

Tenable Nessus: Can I use Nessus to scan third-party networks as a consultant?

Yes, Tenable permits you to use Nessus to scan third-party networks. Nessus Professional is ideal for consultants.

Source
Semperis: How long does forest recovery actually take?

The honest answer is whatever your rehearsal took. The vendor's case is hours instead of days, and automation genuinely removes most manual steps, but the number that matters for your board is the one from a test in your own environment.

Tenable Nessus: Can Nessus perform PCI external scanning?

Yes, you can use Nessus Professional to perform external network scans as required by the PCI DSS 11.2.2 requirement.

Source
Semperis: Does it require agents on domain controllers?

It collects directory changes from the AD replication stream, which is what lets it see changes that bypass the security log. Deployment details vary by product and version, so confirm the exact architecture against your domain controller change-control rules.

Tenable Nessus: What additional features does Nessus Expert provide?

Web application scanning, which is dynamic application security testing (DAST) providing comprehensive visibility and insight into web application security issues; scanning code repositories for vulnerabilities; and assessing external attack surface with subdomain discovery.

Source
Tenable Nessus: What support options exist for Nessus Professional?

Standard Support includes software upgrades, patches, plugin access, and 24x7 support via chat and community portal. Advanced Support adds 24x7 phone access and committed SLAs: P1 less than 2 hours, P2 less than 4 hours, P3 less than 12 hours, P4 less than 24 hours.

Source
Tenable Nessus: How frequently are Nessus plugins updated?

Nessus plugins are updated daily, based on when vendors and security research sites publish new vulnerabilities.

Source
Tenable Nessus: How does licensing work in virtual machine environments?

Whether you are using Nessus in a physical or a virtual environment, the IP addresses or hosts that you are scanning from must be licensed.

Source
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