Prioritizing Vulnerability Fixes

In the ever-evolving landscape of cybersecurity, managing vulnerabilities effectively is paramount to safeguarding your digital assets. At InfoSecRegister, we have developed a structured approach to prioritize vulnerability fixes based on a balanced assessment framework. This article delves into the intricacies of our method, offering a detailed guide for organizations striving to enhance their security posture.

Vulnerability Management

Vulnerability management is a critical component of cybersecurity strategy. However, not all vulnerabilities pose the same level of risk. To allocate resources efficiently and mitigate threats effectively, we need a systematic way to assess and prioritize vulnerabilities. Our approach integrates both the potential impact (severity) and the likelihood of exploitation (exploitation probability) to provide a comprehensive risk assessment.

The 5x5 Risk Matrix

Our 5x5 Risk Matrix combines two primary factors:

1. Severity: The potential impact of the vulnerability.

2. Exploitation Probability: The likelihood that the vulnerability will be exploited.

This matrix helps us determine the overall risk and prioritize vulnerabilities accordingly.

Risk = Severity x Exploitation Probability

CVSS and Severity Calculation

The Common Vulnerability Scoring System (CVSS) is a standardized method for assessing the severity of vulnerabilities. CVSS scores range from 0 to 10, with higher scores indicating more severe vulnerabilities. The CVSS framework considers multiple factors, including:

• Base Score: Assesses the inherent characteristics of the vulnerability.

  • Exploitability Metrics: Includes attack vector, complexity, privileges required, user interaction, and scope.

  • Impact Metrics: Includes confidentiality, integrity, and availability impacts.

• Temporal Score: Adjusts the base score based on factors like exploit code maturity, remediation level, and report confidence.

• Environmental Score: Customizes the score based on the specific environment's impact.

Using CVSS, organizations can derive a numerical score that reflects the severity of a vulnerability. This score can then be mapped to our severity levels:

• CVSS 0.1-3.9: Severity 1 (Very Low) or Severity 2 (Low)

• CVSS 4.0-6.9: Severity 3 (Medium)

• CVSS 7.0-8.9: Severity 4 (High)

• CVSS 9.0-10.0: Severity 5 (Critical)

Severity

Severity measures the potential impact of a vulnerability. It is often based on the Common Vulnerability Scoring System (CVSS), but we have adapted it to suit our needs.

• 1 (Very Low): Minor issues with negligible impact.

• 2 (Low): Issues that pose a low risk, typically affecting non-critical components.

• 3 (Medium): Vulnerabilities that could lead to moderate damage or data exposure.

• 4 (High): Significant vulnerabilities that could lead to major damage or data loss.

• 5 (Critical): Severe vulnerabilities that could lead to complete system compromise or major breaches.

Severity 1 (Very Low)

• Information Disclosure of Non-Sensitive Data: A vulnerability that allows access to log files containing non-sensitive information.

• Minor UI Issues Not Affecting Functionality: Cosmetic issues in the user interface that do not impact the operation of the application.

• Typographical Errors in Documentation: Spelling or grammar mistakes in the product documentation.

• Log File Access with Minimal Information: Access to logs that do not contain sensitive or critical information.

• Non-Privileged Access to Non-Critical System Settings: Ability to change non-essential system settings without elevated privileges.

Severity 2 (Low)

• Minor Denial of Service Under Specific Conditions: A vulnerability that can cause a minor disruption under specific, uncommon conditions.

• Access to Non-Sensitive Customer Data: Ability to access data that does not include PII or financial information.

• Limited User Interface Bypass: Minor bypasses in the UI that do not grant additional privileges or access to sensitive information.

• Outdated Software Versions with Low-Risk Vulnerabilities: Running an outdated version of software that has known low-risk vulnerabilities.

Severity 3 (Medium)

• SQL Injection Without Access to Sensitive Data: An SQL injection vulnerability that can be exploited but does not expose sensitive data.

• Cross-Site Scripting (XSS) Affecting Non-Admin Users: XSS vulnerabilities that affect regular users but not administrators.

• Local File Inclusion Vulnerabilities: Ability to include files from the local file system, potentially exposing non-critical information.

• Weak Encryption for Non-Sensitive Data: Use of weak encryption algorithms for data that is not sensitive.

• Exposure of System Configuration Details: Access to detailed system configuration that could aid in further attacks but does not immediately compromise the system.

Severity 4 (High)

• SQL Injection with Access to Sensitive Data: SQL injection vulnerabilities that can expose sensitive information such as PII or financial data.

• Remote Code Execution in Limited Scope: Ability to execute code remotely under specific conditions, potentially compromising parts of the system.

• Vulnerabilities Affecting Admin Users: XSS, CSRF, etc. vulnerabilities that can impact administrative users, potentially leading to elevated privileges.

• Authentication Bypass Vulnerabilities: Flaws that allow attackers to bypass authentication mechanisms.

• Privilege Escalation on Non-Critical Systems: Ability to escalate privileges on systems that are important but not critical.

Severity 5 (Critical)

• Remote Code Execution with Full System Access: Vulnerabilities that allow remote attackers to execute code with full control over the system.

• Complete Authentication Bypass: Flaws that allow attackers to completely bypass authentication mechanisms, gaining full access.

• Arbitrary Code Execution: Ability to execute any code on the target system, potentially leading to complete system compromise.

• Privilege Escalation to Root/Admin: Vulnerabilities that allow attackers to escalate privileges to root or administrative levels.

• Full Database Dump via SQL Injection: SQL injection vulnerabilities that can be exploited to dump the entire database, exposing all stored data.

Exploitation Probability

Exploitation probability measures how likely it is that a vulnerability will be exploited. This factor considers various elements, including the ease of finding and exploiting the vulnerability, the availability of Proof of Concept (PoC) exploits, and the presence of compensating controls.

High-Level Exploitation Probability Definitions

• 1 (Very Low): Extremely unlikely to be exploited.

• 2 (Low): Unlikely to be exploited.

• 3 (Medium): Possible but not easy to exploit.

• 4 (High): Likely to be exploited.

• 5 (Very High): Very likely to be exploited.

Exploitation Probability 1 (Very Low)

• Extremely Difficult to Discover: The vulnerability is hidden and requires extensive effort to uncover.

• Complex Exploit Requiring Rare Conditions: Exploitation requires a very specific and uncommon set of conditions.

• No Known Exploits or PoCs: There are no public exploits or proof-of-concept codes available.

• Requires Physical Access to an Isolated Environment: Exploitation necessitates physical access to a highly secure, isolated environment.

• Requires Highly Specialized Knowledge or Tools: Only attackers with specialized knowledge and tools can exploit this vulnerability.

Exploitation Probability 2 (Low)

• Somewhat Difficult to Discover: The vulnerability is not immediately obvious and requires significant effort to identify.

• Exploit Requires Specific Conditions: Certain conditions must be met for the exploit to be feasible.

• Limited Known Exploits or PoCs: Few known exploits or proof-of-concept codes are available, and they are not widely distributed.

• Requires Physical Access with Some Difficulty: Physical access is necessary but not easy to achieve.

• Requires Specialized Knowledge or Tools: Exploitation requires knowledge or tools that are not commonly available.

Exploitation Probability 3 (Medium)

• Moderately Difficult to Discover: The vulnerability can be discovered with moderate effort.

• Exploit Requires Some Specific Conditions: Specific conditions are needed, but they are not overly complex to achieve.

• Known Exploits or PoCs with Limited Distribution: Exploits or PoCs exist but are not widely available.

• Can Be Exploited Remotely but with Limited Success: Remote exploitation is possible, but it is not guaranteed to succeed.

• Requires Moderate Knowledge or Tools: Exploitation requires a moderate level of knowledge or tools.

Exploitation Probability 4 (High)

• Easy to Discover: The vulnerability is relatively easy to identify.

• Exploit Requires Minimal Specific Conditions: Few conditions are needed for the exploit to work.

• Widely Available PoCs: Proof-of-concept codes are readily available.

• Can Be Exploited Remotely with Some Effort: Remote exploitation is feasible with some effort.

• Requires Basic Knowledge or Tools: Only basic knowledge or tools are necessary for exploitation.

Exploitation Probability 5 (Very High)

• Very Easy to Discover: The vulnerability is immediately apparent.

• Exploit Requires No Specific Conditions: Exploitation requires no special conditions.

• Publicly Available PoCs and Exploits: Exploits and PoCs are widely available and well-documented.

• Can Be Exploited Remotely with Ease: Remote exploitation is straightforward.

• Requires No Specialized Knowledge or Tools: Exploitation can be performed with basic, commonly available tools.

Risk Ratings and Recommended Actions

Critical Risk

• Immediate threat with the potential for severe damage or complete system compromise.

• Actions: Release updates immediately. Prioritize patching and remediation. Notify affected customers and provide guidance.

High Risk

• Significant threat with potential for major damage or data loss.

• Actions: Address as soon as possible. Deploy patches and updates within a short timeframe. Inform customers of the issue and recommend temporary mitigation measures.

Medium Risk

• Moderate threat that could lead to damage or data exposure under certain conditions.

• Actions: Schedule updates in the next regular release cycle. Monitor for any signs of exploitation. Communicate with customers about the planned fix.

Low Risk

• Low threat with minimal potential impact.

• Actions: Address in a future update. Include fixes in the next planned maintenance release. Inform customers if necessary.

Very Low Risk

• Negligible threat with little to no impact.

• Actions: Consider addressing in future updates as part of general improvements. Inform customers if relevant.

Example Application

To illustrate how this framework works in practice, consider the following examples:

• A critical vulnerability (Severity 5) with a medium exploitation probability (3) results in a High risk level. This vulnerability would be prioritized for immediate action.

• A low-severity vulnerability (Severity 2) with a very low exploitation probability (1) results in a Very Low risk level. This can be scheduled for a future update without immediate concern.

By balancing the severity and exploitation probability, we can make informed decisions about which vulnerabilities to address first, ensuring that our resources are used effectively to protect our customers.