PHP, like any other programming technology, is not immune to vulnerabilities. Web applications, most of which use PHP, are frequently targeted by malicious parties looking to exploit these vulnerabilities. Therefore, it is crucial for developers and managers of PHP applications to be able to identify and address these vulnerabilities effectively.
What Are PHP Vulnerabilities?
A PHP vulnerability refers to an exploitable flaw in a PHP application that can allow unauthorized access to underlying systems. These vulnerabilities can range from code injection and broken access control to security misconfigurations and cryptographic failures.
Example of a PHP Vulnerability
Let’s take the recent vulnerability ‘OOB read due to insufficient input validation in imageloadfont()’ (CVE-2022-31630) as an example. This flaw enables remote attackers to pass specially crafted data to the web application, triggering an out-of-bounds read error and potentially accessing sensitive information stored in memory.
Preventing Exposure to PHP Vulnerabilities
To minimize the risks associated with PHP vulnerabilities, teams should follow application security best practices. This includes conducting threat modeling using the STRIDE method to identify potential vulnerabilities and performing risk assessments with the DREAD framework to gauge the likelihood of different types of attacks.
Since most web applications use PHP as their server-side language, keeping PHP versions up to date is essential. Implementing the methodologies mentioned above, along with regular updates, is crucial for maintaining the security of web applications.
How Are PHP Vulnerabilities Disclosed?
Both Zend and the PHP community actively work to discover vulnerabilities present in the PHP engine and its various extensions. The findings of this ongoing process are published as CVEs (Common Vulnerabilities and Exposures) by the community and in the PHP Security Center. These CVE entries help teams assess and mitigate vulnerabilities in their PHP applications.
Reporting and Responding to PHP Vulnerabilities
If anyone within the PHP ecosystem identifies a vulnerability, they can securely report it to the PHP security team. The team then verifies the issue and collaborates with the reporter to develop a patch. Once the fix is validated, it is merged into the appropriate code repository, with the information obfuscated to prevent unauthorized access.
Before the official announcement of a CVE, it is assigned a unique identifier and associated with the patch. However, the specific details of the vulnerability are not disclosed until after the release. Additionally, the PHP security team coordinates with package maintainers from various operating system distributions to ensure timely release of binaries alongside the source code.
This well-established process allows teams to patch vulnerabilities swiftly, minimizing the possibility of exploitation by malicious actors.
Evaluating PHP Vulnerability Severity
Not all PHP vulnerabilities carry the same level of risk. To assess vulnerabilities accurately, organizations, such as the National Institute of Standards and Technology (NIST), have developed standardized criteria. The National Vulnerability Database (NVD) provides the Common Vulnerability Scoring System (CVSS), which enables software teams to determine the severity of a vulnerability promptly.
CVSS v3.0 Severity Levels
The severity levels in CVSS v3.0 are divided into five categories based on the base score range:
- 0.0: None
- 0.1-3.9: Low
- 4.0-6.9: Medium
- 7.0-8.9: High
- 9.0-10.0: Critical
Calculating Vulnerability Severity
NIST offers a calculator to determine the severity of vulnerabilities, considering factors such as the attack vector, complexity, privileges required, user interaction, scope, and impact on confidentiality, integrity, and availability.
Source: NVD CVSS v3 Calculator
Looking back at the earlier example (CVE-2022-31630), you can see that multiple base scores were assigned. The NVD group and PHP Group assessed the CVE differently, with the NVD group considering it more severe based on their vector selections.
Source: CVE-2022-31630 Details
Assessing and mitigating PHP vulnerabilities can be complex and time-consuming, but it is a vital part of PHP development and management. Failing to patch CVEs can expose teams to devastating exploits that can impact organizational success.
We highly recommend bookmarking our PHP Security Center page for ongoing updates and maintaining full visibility into the PHP versions you deploy. If you have PHP versions that have reached end of life and require patching, explore our PHP LTS offerings.
Keep Your EOL PHP Patched With LTS From ProgramMatek
ProgramMatek offers PHP LTS support for end-of-life PHP versions, backed by guaranteed SLAs and support from our team of experts.
See Our LTS Options
- Solution – ProgramMatek PHP Consulting Services
- Solution – ProgramMatek PHP Security and Consulting Services
- Resource – ProgramMatek PHP Security Center
- Blog – Changes to Watch in PHP 8.3
- Blog – Why Good PHP Monitoring Matters
- Blog – Mitigating CVE-2023-0662
- Blog – The State of WordPress PHP Support
- Blog – Using Containers to Improve PHP Application Security
- Blog – 6 PHP Security Best Practices
- Blog – Setting Your PHP 7.4 Migration Strategy
- Blog – PHP 7.4 EOL Is Here: Are Your Applications Secure?
- Blog – Understanding CVEs and CVSS Scores
- Blog – Are You Ready for PHP 8.0 EOL?
- White Paper – The Costs of Building PHP In-House
- White Paper – Planning Your Next PHP Migration