CVE-2017-8923 : Security Advisory and Response
Learn about CVE-2017-8923, a PHP vulnerability in zend_string_extend function allowing remote attackers to cause denial of service. Find mitigation steps here.
PHP through version 7.1.5 is vulnerable to a denial of service attack due to a flaw in the zend_string_extend function.
Understanding CVE-2017-8923
This CVE involves a vulnerability in PHP versions up to 7.1.5 that can be exploited by remote attackers to cause a denial of service.
What is CVE-2017-8923?
The zend_string_extend function in PHP does not prevent changes to string objects that result in a negative length, potentially leading to a denial of service or other impacts.
The Impact of CVE-2017-8923
- Remote attackers can exploit this vulnerability to cause a denial of service, potentially resulting in an application crash.
- Attackers may also leverage a script's use of .= with a long string to have other unspecified impacts.
Technical Details of CVE-2017-8923
PHP versions up to 7.1.5 are affected by this vulnerability.
Vulnerability Description
The zend_string_extend function in PHP does not have safeguards against modifications to string objects that lead to a negative length.
Affected Systems and Versions
- Product: Not applicable
- Vendor: Not applicable
- Versions: Up to PHP 7.1.5
Exploitation Mechanism
Attackers can exploit this vulnerability remotely to cause a denial of service by manipulating string objects.
Mitigation and Prevention
It is crucial to take immediate steps to address and prevent exploitation of this vulnerability.
Immediate Steps to Take
- Update PHP to a version beyond 7.1.5 to mitigate the vulnerability.
- Monitor for any unusual activities that could indicate an ongoing attack.
Long-Term Security Practices
- Regularly update PHP and other software to the latest versions to patch known vulnerabilities.
- Implement secure coding practices to prevent similar vulnerabilities in the future.
- Conduct regular security assessments and audits to identify and address potential weaknesses.
- Stay informed about security advisories and best practices in PHP development.
Patching and Updates
Ensure that PHP is regularly updated to the latest secure version to protect against known vulnerabilities.