CVE-2012-5657 in Zend
Summary
by MITRE
The (1) Zend_Feed_Rss and (2) Zend_Feed_Atom classes in Zend_Feed in Zend Framework 1.11.x before 1.11.15 and 1.12.x before 1.12.1 allow remote attackers to read arbitrary files, send HTTP requests to intranet servers, and possibly cause a denial of service (CPU and memory consumption) via an XML External Entity (XXE) attack.
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2012-5657 represents a critical security flaw in the Zend Framework 1.11.x and 1.12.x versions, specifically affecting the Zend_Feed_Rss and Zend_Feed_Atom classes. This vulnerability stems from insufficient input validation and improper handling of XML entities within the feed processing components, creating a pathway for malicious actors to exploit XML External Entity (XXE) attacks. The flaw allows attackers to manipulate the XML parsing behavior of these classes, potentially enabling unauthorized file access, internal network reconnaissance, and resource exhaustion attacks.
The technical implementation of this vulnerability occurs when the affected Zend Framework classes process XML feeds without adequate sanitization of external entity declarations. When parsing RSS or Atom feeds, these components fail to properly restrict the resolution of external entities, allowing attackers to craft malicious XML payloads that reference external resources or perform arbitrary file reads. The XXE attack vector enables threat actors to leverage the framework's XML parsing capabilities to access local files on the server, bypass firewalls through internal network requests, and consume excessive system resources. This vulnerability aligns with CWE-611, which specifically addresses improper restriction of XML external entity reference, and represents a classic example of how XML processing libraries can become attack surfaces when external entity handling is not properly controlled.
The operational impact of CVE-2012-5657 extends beyond simple data theft, creating multiple attack vectors that can compromise system integrity and availability. Remote attackers can exploit this vulnerability to perform reconnaissance activities by accessing internal server files that should remain protected, potentially gaining information about the internal network structure and system configurations. The ability to send HTTP requests to intranet servers through XXE attacks enables attackers to map internal network topology and identify vulnerable internal systems. Additionally, the vulnerability can be leveraged to cause denial of service conditions by crafting XML payloads that consume excessive CPU cycles or memory resources, leading to system instability or complete service disruption. This attack pattern corresponds to several techniques documented in the MITRE ATT&CK framework under the T1059 and T1069 categories, specifically targeting remote code execution and network reconnaissance capabilities.
Organizations utilizing affected versions of Zend Framework should implement immediate mitigations to address this vulnerability. The primary solution involves upgrading to patched versions of Zend Framework 1.11.15 or 1.12.1, which include proper XML entity handling and external entity restrictions. System administrators should also implement XML parsing restrictions within their applications, ensuring that feed processing components disable external entity resolution and do not allow arbitrary file access. Network segmentation and firewall rules can help limit the potential impact of internal network reconnaissance attempts, while monitoring systems should be configured to detect unusual patterns of file access or HTTP requests originating from application servers. Security teams should conduct comprehensive vulnerability assessments to identify all systems using affected framework versions and implement proper input validation for all XML processing components to prevent similar vulnerabilities from emerging in other parts of the application stack.