Multiple Vulnerabilities in PHP Allow for Information Disclosure, DoS, SSRF, and Unknown Impacts

Multiple vulnerabilities in PHP allow a remote attacker to disclose information, cause a denial-of-service condition, perform a Server-Side Request Forgery (SSRF) attack, or achieve other unspecified impacts. The CERT-Bund advisory highlights the potential for significant compromise due to the diverse nature of these flaws. Defenders should be aware of potential exploitation attempts targeting PHP applications and infrastructure, especially given the wide deployment of PHP in web environments. The lack of specific CVEs in the advisory makes targeted patching and mitigation challenging, requiring a more comprehensive defensive strategy.

Attack Chain

1. The attacker identifies a vulnerable PHP application or server.
2. The attacker crafts a malicious request designed to exploit an information disclosure vulnerability (T1592).
3. The vulnerable PHP application processes the request, unintentionally revealing sensitive data.
4. Alternatively, the attacker sends a specially crafted request designed to trigger a denial-of-service (DoS) condition (T1499).
5. The PHP application crashes or becomes unresponsive due to the DoS attack.
6. As another alternative, the attacker crafts a request to exploit a Server-Side Request Forgery (SSRF) vulnerability (T1190).
7. The vulnerable PHP application makes unauthorized requests to internal resources or external services on behalf of the attacker.
8. The attacker may gain unauthorized access to internal systems or sensitive information through the SSRF attack or cause other, unspecified impacts.

Impact

Successful exploitation of these PHP vulnerabilities can lead to sensitive information disclosure, denial-of-service conditions affecting web applications, and unauthorized access to internal resources through SSRF attacks. The “unknown impacts” mentioned in the advisory suggest the potential for even more severe consequences. The wide deployment of PHP means a successful attack could affect numerous organizations and users.

Recommendation

• Monitor web server logs for suspicious activity indicative of exploitation attempts targeting PHP applications (see example Sigma rule for SSRF detection)
• Implement web application firewalls (WAFs) to filter malicious requests and protect against common PHP exploits.
• Since the advisory lacks specific CVEs, conduct thorough security audits and penetration testing of PHP applications to identify and address potential vulnerabilities.