CVE-2014-3597 in PHP
Summary
by MITRE
Multiple buffer overflows in the php_parserr function in ext/standard/dns.c in PHP before 5.4.32 and 5.5.x before 5.5.16 allow remote DNS servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted DNS record, related to the dns_get_record function and the dn_expand function. NOTE: this issue exists because of an incomplete fix for CVE-2014-4049.
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Analysis
by VulDB Data Team • 02/11/2022
The vulnerability identified as CVE-2014-3597 represents a critical buffer overflow condition affecting PHP applications that process DNS records through the dns_get_record function. This issue specifically targets the php_parserr function within the ext/standard/dns.c file of PHP's source code, creating a security risk that can be exploited by remote DNS servers to either crash applications or potentially execute arbitrary code. The vulnerability affects PHP versions prior to 5.4.32 and 5.5.x versions before 5.5.16, making it a widespread concern across multiple PHP release lines. The flaw manifests when the dns_get_record function processes malformed DNS records, particularly those containing crafted data that exceeds allocated buffer boundaries during parsing operations. This vulnerability stems from an incomplete remediation of a previous issue, CVE-2014-4049, which demonstrates the complexity of addressing buffer overflow vulnerabilities in network protocol handling code.
The technical implementation of this vulnerability involves the dn_expand function and php_parserr function working together to parse DNS records received from remote servers. When PHP encounters DNS records that contain oversized or malformed data structures, the buffer management within these functions fails to properly validate input boundaries. The buffer overflow occurs during the expansion of DNS compressed names, where the dn_expand function attempts to decompress DNS names that exceed expected size limits. This improper boundary checking allows attackers to craft malicious DNS responses that, when processed by PHP applications using dns_get_record, can overwrite adjacent memory locations. The vulnerability's impact extends beyond simple denial of service since the memory corruption can potentially be leveraged for code execution, depending on the specific memory layout and the attacker's ability to control the overflowed data.
The operational impact of CVE-2014-3597 is significant for PHP applications that rely on DNS resolution for various functions including email validation, domain verification, and network service discovery. Applications using the dns_get_record function are particularly vulnerable when they process DNS responses from untrusted sources without proper input sanitization. Attackers can exploit this vulnerability by setting up malicious DNS servers that respond to queries with specially crafted records designed to trigger the buffer overflow. The consequences include application crashes that lead to denial of service conditions, potentially affecting entire web applications or services that depend on DNS resolution. In scenarios where the buffer overflow can be controlled to overwrite critical memory regions, attackers might achieve arbitrary code execution, potentially compromising the entire hosting environment. This vulnerability particularly affects web applications that perform DNS lookups as part of their normal operations, making it a prime target for attackers seeking to exploit PHP-based systems.
Mitigation strategies for CVE-2014-3597 primarily focus on upgrading affected PHP installations to versions that contain proper buffer boundary checks and input validation. Organizations should immediately upgrade to PHP 5.4.32 or PHP 5.5.16 and later releases where the vulnerability has been fully addressed. Additionally, implementing proper input validation and sanitization within applications that use dns_get_record can provide defense-in-depth protection. Security measures should include monitoring DNS query responses for unusual patterns and implementing network-level controls to restrict DNS traffic from untrusted sources. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation that can lead to memory corruption. From an attack perspective, this vulnerability maps to ATT&CK technique T1059.007, which covers command and script injection, as the potential for code execution makes it a valuable target for attackers seeking persistent access to compromised systems. Network administrators should also consider implementing DNS filtering and monitoring solutions to detect and prevent exploitation attempts against vulnerable PHP applications.