External Attack Surface Prioritization
External Attack Surface Prioritization (EASP) is a specialized, risk-based approach within cybersecurity that focuses solely on an organization's publicly exposed assets and digital footprint. It is the practical execution of the "Prioritization" phase of the CTEM framework as applied to the external attack surface.
The core goal of EASP is to distinguish the handful of most dangerous, exploitable external exposures from the potentially thousands of discovered assets, misconfigurations, and vulnerabilities.
Key Principles of EASP
Adversary-Centric Focus: EASP assumes an attacker will target the weakest, most exposed asset. Therefore, it prioritizes assets based on their exploitability and accessibility from the public internet. This means an easily accessible, unpatched server is prioritized higher than a patched server behind a complex internal firewall, even if they share the same vulnerability.
Risk = Likelihood x Impact: EASP uses a formal model to rank exposures:
Likelihood (Threat Intelligence): It heavily weights external threat intelligence. An exposure is prioritized if it is associated with a Known Exploited Vulnerability (KEV), has a high Exploit Prediction Scoring System (EPSS) score, or is confirmed to be targeted by specific ransomware groups.
Impact (Business Context): It layers the business context over the external finding. A publicly exposed API is prioritized higher than a temporary staging subdomain if the API handles customer data or critical transactions.
Validation is Mandatory: EASP requires validation before prioritization. An exposure is only assigned a high score if it is confirmed to be reachable and exploitable from the outside. Validation includes checking for exposed credentials, active administrative interfaces, and open, sensitive ports.
Prioritization Metrics: EASP translates complex data into simple, actionable metrics for remediation teams:
Security Ratings: A consolidated, easy-to-understand score (e.g., A-F grade) for the entire organization or a specific external asset.
Exposure-Specific Ranking: A definitive list that dictates the order of remediation, focusing on closing the external "front door" first.
EASP filters the overwhelming noise of a global attack surface down to the few, clear "must-fix" issues that pose the most significant and most immediate threat of initial access to the organization.
External Attack Surface Prioritization (EASP) is the critical process of filtering the massive amount of data generated by External Attack Surface Management (EASM) tools down to the few, most dangerous, exploitable issues. ThreatNG is designed to execute this prioritization by quantifying the risk of external exposures based on threat likelihood, business impact, and validation status.
ThreatNG's Role in External Attack Surface Prioritization
1. External Discovery and Continuous Monitoring (Defining the Surface)
The External Discovery and Continuous Monitoring capabilities ensure the EASP process uses a complete and current list of all internet-facing assets—the "surface" to be prioritized. Without a complete inventory, prioritization is inherently flawed.
Example of ThreatNG Helping: An organization has hundreds of subdomains. ThreatNG automatically discovers and monitors them, ensuring that a recently deployed, high-risk
api.beta-test.comsubdomain is included in the EASP process immediately, preventing a blind spot from being introduced.
2. Intelligence Repositories (The Likelihood Factor)
ThreatNG uses its Intelligence Repositories (DarCache) to assign a likelihood score based on real-world threat activity, which is the most critical metric in EASP.
Example of ThreatNG Helping: The DarCache Vulnerability repository integrates KEV (Known Exploited Vulnerabilities) and EPSS (Exploit Prediction Scoring System) intelligence. An exposed asset is found to have a high-severity CVE. ThreatNG checks DarCache and finds the CVE is actively being exploited (KEV status confirmed). This intelligence immediately overrides the base severity, prioritizing the exposure as "Critical" because its likelihood of exploitation has been proven.
3. External Assessment (The Validation and Impact Factor)
The External Assessment capabilities provide the necessary validation that an exposure is exploitable from the outside and assesses its potential impact, two pillars of EASP.
Example of ThreatNG Helping (Validation): An assessment finds high Subdomain Takeover Susceptibility (based on Domain Intelligence). This is validation that an attacker has an immediate, clear exploit path to hijack a specific DNS record. This confirmed exploitability places the issue at a higher priority than an unvalidated theoretical risk.
Example of ThreatNG Helping (Impact): The assessment includes Breach & Ransomware Susceptibility, factoring in findings from Dark Web Presence, Sentiment, and Financials. If an exposed asset is linked to recent SEC Form 8-K filings or ransomware gang activity, the Impact Factor is heightened, thereby accelerating its priority score.
4. Investigation Modules (Confirmation and Context)
The Reconnaissance Hub provides the definitive, granular evidence needed to validate and give context to a high-priority exposure before remediation is mobilized.
Example of ThreatNG Helping: The Sensitive Code Exposure module validates a finding of an exposed API by confirming that a plaintext AWS Access Key ID is present in a public GitHub repository. This absolute proof of exploitability ensures this credential rotation task receives the highest possible priority score for immediate remediation.
5. Reporting (The Final Priority Output)
Reporting aggregates the risk-based scores into actionable formats that drive the final remediation order, completing the EASP cycle.
Example of ThreatNG Helping: ThreatNG's Security Ratings (A-F grade) and Prioritized reports are the final EASP output. They translate complex scoring into a simple, quantitative metric that security leadership uses to compare the risk of different business units or external vendors, ensuring resources flow to the lowest-rated, highest-risk areas.
Cooperation with Complementary Solutions
ThreatNG's EASP insights provide pre-validated and prioritized tasks to internal systems, ensuring internal remediation efforts are aligned with external threats.
ThreatNG and a Security Information and Event Management (SIEM) Solution:
Cooperation: ThreatNG informs the SIEM of the validated, highest-priority external risks that pose an immediate initial-access threat.
Example: EASP prioritizes an asset as "Critical" because a Sensitive Port is open and Compromised Credentials are found on the Dark Web. ThreatNG sends this specific credential list to the SIEM, which uses it to create a high-fidelity internal watch list. The SIEM will then generate an immediate, high-severity alert if those credentials attempt to log in, connecting the external prioritization directly to internal defense.
ThreatNG and a Vulnerability and Patch Management (VPM) Tool:
Cooperation: ThreatNG provides the VPM tool with a short, highly prioritized list of vulnerabilities to patch, based on external threat likelihood and asset exposure.
Example: The EASP process flags a web server vulnerability as "Critical" because it has high EPSS and KEV status. This specific finding is sent to the VPM tool, which uses the "Critical" priority flag to create an emergency patch ticket immediately, overriding standard patching cycles for this one externally exposed asset.
