Primary Refresh Token
A Primary Refresh Token (PRT) is a critical authentication artifact used in modern identity management systems, most notably within the Microsoft Entra ID (formerly Azure Active Directory) ecosystem. It is a specialized JSON Web Token (JWT) issued to a device that has been successfully registered or joined to the identity provider. The PRT serves as a persistent proof of identity, enabling Seamless Single Sign-On (SSO) across applications and web services without requiring users to repeatedly enter their credentials.
In a cybersecurity context, the PRT is considered one of the most valuable targets for attackers because it represents a successful authentication event, often including proof that Multi-Factor Authentication (MFA) was performed.
The Role of PRTs in Single Sign-On (SSO)
The primary purpose of a PRT is to balance security with user productivity. By caching authentication state on a trusted device, the PRT provides several key functions:
Persistent Authentication: Once a user logs into a device joined to the corporate domain, the identity provider issues a PRT. This token can remain valid for extended periods (often up to 14 days), renewing automatically as long as the device remains in use.
Proof of MFA: When a user completes an MFA challenge, that claim is embedded within the PRT. Subsequent requests for access to other applications can use the PRT to "prove" the user has already passed MFA, allowing them to skip additional prompts.
Device-Bound Security: PRTs are cryptographically tied to the specific device they were issued to. This is typically achieved by using a Trusted Platform Module (TPM) to ensure the token cannot be easily copied and used on another machine.
Cybersecurity Risks: PRT Theft and Hijacking
Because a PRT essentially acts as a "Golden Ticket" to cloud resources, it is a major target for modern malware, particularly infostealers.
Token Theft and Replay: Advanced infostealer malware like Lumma or RedLine is designed to extract PRTs from the local security authority or browser memory. If an attacker successfully exfiltrates a PRT, they can attempt to "replay" it on their own infrastructure to hijack the user's entire cloud identity.
Bypassing MFA: Because the PRT stores the "MFA claim," an attacker who successfully hijacks a PRT does not need to know the user's password or possess the user's physical MFA device. The identity provider sees the valid PRT and assumes the session is already fully authenticated.
Lateral Movement: With a valid PRT, an attacker can move laterally across all applications integrated with the organization's Single Sign-On provider, including email, cloud storage, and administrative portals.
Frequently Asked Questions About Primary Refresh Tokens
How is a PRT different from a standard Refresh Token?
A standard refresh token is typically limited to a single application. In contrast, a Primary Refresh Token is a global artifact that works across the entire identity ecosystem. While a standard token might get you into one app, a PRT provides the credentials necessary to obtain access tokens for any application the user is authorized to use.
Where is the Primary Refresh Token stored?
On Windows devices, the PRT is managed by the Cloud Experience Host and the Web Account Manager (WAM). It is typically protected by the Trusted Platform Module (TPM) to prevent unauthorized extraction, though sophisticated malware can sometimes bypass these protections if it achieves administrative privileges.
How can organizations prevent PRT theft?
Defending against PRT theft requires a multi-layered approach. Key strategies include enforcing device compliance policies (ensuring tokens work only on managed, healthy devices), using hardware-backed security keys for MFA, and implementing "Token Binding" to cryptographically bind the token to the specific TLS connection of the legitimate user.
Can a PRT be revoked if a device is lost?
Yes. Administrators can revoke a PRT by disabling the user's account, changing the user's password, or using specific "Revoke Sessions" commands within the identity provider's administrative portal. This invalidates the PRT and forces a full re-authentication on the next access attempt.
How ThreatNG Neutralizes PRT Theft and Infostealer Risks
The industrialization of cybercrime has turned session tokens and PRTs into the primary currency for Initial Access Brokers. Because these tokens are often harvested from unmanaged personal devices (BYOD), internal security tools are frequently blind to the compromise. ThreatNG provides a comprehensive, outside-in defense framework designed to detect, contextualize, and neutralize these stolen identities before they result in a breach.
Continuous Monitoring and External Discovery
ThreatNG acts as a frictionless, agentless engine that secures the external attack surface through automated, connectorless discovery. It identifies the foundational exposures that cause major breaches by mapping the digital footprint from the outside in.
Unmanaged Asset Visibility: ThreatNG performs purely external, unauthenticated discovery, which is critical for finding risks on unmanaged personal devices or home networks where employees access corporate resources.
Shadow IT Identification: The platform continuously discovers unknown subdomains, rogue cloud accounts, and forgotten marketing sites. These are often the first targets for an adversary who has acquired a stolen PRT.
Persistent Perimeter Watch: Through continuous monitoring, ThreatNG ensures that any change in the external attack surface is immediately cataloged and assessed for risk.
Precision External Assessment
ThreatNG translates technical findings into strategic narratives using structured security ratings (A-F). These assessments provide a clear view of an organization's susceptibility to session hijacking and credential abuse.
Web Application Hijack Susceptibility: This assessment evaluates the risk of token theft by analyzing subdomains for missing security headers. Specifically, it looks for the absence of Content-Security-Policy (CSP), HTTP Strict-Transport-Security (HSTS), X-Content-Type, and X-Frame-Options.
Example: If a subdomain is graded as an "F" because it lacks HSTS and CSP headers, it is highly vulnerable to script injection and "Adversary-in-the-Middle" (AiTM) attacks that can harvest session tokens in real-time.
Subdomain Takeover Susceptibility: ThreatNG uses DNS enumeration to identify CNAME records pointing to inactive third-party services such as AWS, Heroku, or Vercel.
Example: An organization may have a "dangling" DNS record pointing to a decommissioned Azure storage bucket. ThreatNG identifies this, preventing an attacker from claiming that bucket and using the trusted corporate subdomain to host malicious code that steals PRTs from visiting employees.
In-Depth Investigation Modules
ThreatNG uses granular investigation modules to uncover the specific "side doors" that adversaries use after acquiring a stolen token.
Sensitive Code Exposure: This module discovers public code repositories and identifies leaked secrets. It scans for exposed credentials such as AWS Access Key IDs, Stripe API keys, Slack Webhooks, and database configuration files.
Example: If an attacker finds a developer’s session token in an infostealer log, they will immediately search for public GitHub repositories. ThreatNG identifies these exposures first, allowing the organization to rotate secrets before the attacker uses the stolen session to download proprietary source code.
Technology Stack Discovery: This module catalogs thousands of technologies that comprise the external attack surface, identifying which cloud platforms and IAM solutions are in use.
Example: By identifying that an organization uses Microsoft Entra ID, ThreatNG focuses its intelligence gathering on specific PRT exposures unique to that environment, ensuring high-relevance alerts.
Intelligence Repositories (DarCache)
ThreatNG uses its proprietary Data Aggregation Reconnaissance Cache (DarCache) to turn chaotic dark web data into actionable truth.
DarCache Infostealer: This repository continuously archives and normalizes logs from dark web marketplaces and Telegram channels. It specifically targets analyzed logs containing usernames, passwords, cookies, and PRTs.
Legal-Grade Attribution: ThreatNG uses multi-source data fusion to definitively prove that a stolen credential or token belongs to the organization. This eliminates the "Contextual Certainty Deficit"—the gap between having an alert and knowing if it is a real risk.
Example of Use: When a PRT is uploaded to a cybercrime aggregator like Moon Cloud or Omega Cloud, DarCache instantly indexes it. ThreatNG provides the security team with the exact user identity and attributing log source, enabling immediate session invalidation.
Actionable Reporting and DarChain Attack Paths
ThreatNG eliminates alert fatigue by providing contextual, blueprint-style reporting that maps the adversary's journey.
DarChain (Attack Path Intelligence): DarChain transforms a flat list of stolen credentials into a structured threat model. It visually maps the precise exploit chain an adversary might follow, correlating a specific stolen credential directly to an exposed network port or API.
Boardroom-Ready Ratings: Findings are grouped into prioritized grades, allowing security leaders to communicate risk effectively to executive leadership and justify security investments.
Cooperation with Complementary Solutions
ThreatNG serves as the definitive external intelligence layer, enhancing the effectiveness of existing security tools.
Identity and Access Management (IAM): ThreatNG acts as an early warning system for IAM platforms. When a compromised PRT is found on the dark web, ThreatNG feeds this data to the IAM solution, which can then trigger a global password reset and invalidate all active cloud sessions for the affected user only.
Cyber Asset Attack Surface Management (CAASM): CAASM tools manage known, managed assets. ThreatNG provides the "outside-in" view, feeding the CAASM system with newly discovered shadow IT and unmanaged devices compromised by infostealers.
Breach and Attack Simulation (BAS): ThreatNG expands the scope of BAS tools by feeding them a dynamic list of real-world exposures and leaked credentials, ensuring simulations test the paths of least resistance that actual attackers target.
Cyber Risk Quantification (CRQ): CRQ solutions often rely on statistical guesses. ThreatNG acts as a "telematics chip," providing behavioral facts—like open ports or dark web chatter—to dynamically adjust the financial risk likelihood in the CRQ model.
Frequently Asked Questions
How does ThreatNG detect Primary Refresh Token (PRT) theft?
ThreatNG’s DarCache Infostealer module continuously monitors and parses illicit Telegram channels and dark web log clouds. It identifies compromised PRTs and session cookies the moment they are uploaded, providing the security team with the exact user identity and the attributing log source.
What is the difference between a password breach and session token theft?
A password breach involves the theft of static login credentials. Session token theft involves stealing the "proof of authentication" (e.g., a PRT) that is generated after the password and MFA have been verified. This allows an attacker to skip those steps entirely and hijack an active session.
Why is external discovery important for stopping infostealers?
Internal security agents can only see managed devices. Infostealers frequently infect unmanaged personal devices (BYOD) used for remote work. ThreatNG uses external discovery to find these "invisible" infections by seeing the stolen corporate data where it ends up—in the criminal underground.
How does DarChain help prevent ransomware?
Initial Access Brokers use stolen credentials to find entry points for ransomware syndicates. By using DarChain to map the attack path from a stolen credential to an exposed network port, ThreatNG allows organizations to break the adversary kill chain before the ransomware is ever deployed.
