CVE-2017-12074 in DNS Server
Summary
by MITRE
Directory traversal vulnerability in the SYNO.DNSServer.Zone.MasterZoneConf in Synology DNS Server before 2.2.1-3042 allows remote authenticated attackers to write arbitrary files via the domain_name parameter.
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability identified as CVE-2017-12074 represents a critical directory traversal flaw within Synology DNS Server's SYNO.DNSServer.Zone.MasterZoneConf component. This weakness exists in versions prior to 2.2.1-3042 and enables remote authenticated attackers to exploit the system by manipulating the domain_name parameter. The vulnerability stems from inadequate input validation and sanitization mechanisms that fail to properly restrict file system access paths, allowing malicious actors to traverse directory structures and write arbitrary files to sensitive locations within the system.
The technical implementation of this flaw involves the manipulation of the domain_name parameter through crafted input that bypasses normal access controls. When an authenticated user submits a specially crafted domain name value, the system processes this input without proper validation, enabling path traversal attacks. This vulnerability specifically affects the DNS server's zone configuration handling mechanism where the system should validate and sanitize all user-provided input before processing it in file system operations. The flaw allows attackers to write files to arbitrary locations, potentially leading to privilege escalation, data corruption, or system compromise.
From an operational perspective, this vulnerability poses significant risks to Synology NAS environments as it requires only authenticated access to exploit, making it particularly dangerous in scenarios where users have legitimate administrative privileges. Attackers can leverage this weakness to place malicious files in critical system directories, potentially leading to persistent backdoors or system-wide compromise. The impact extends beyond simple file manipulation as it can enable attackers to modify DNS zone configurations, potentially redirecting traffic or disrupting network services. This vulnerability aligns with CWE-22 Directory Traversal and follows patterns commonly associated with privilege escalation attacks in network services.
Organizations should implement immediate mitigation strategies including applying the vendor-provided patch to version 2.2.1-3042 or higher, which addresses the input validation weakness in the domain_name parameter handling. Network segmentation and access control measures should be strengthened to limit administrative access to only trusted users and systems. Monitoring should be enhanced to detect unusual file system operations or configuration changes in DNS server components. Security teams should also consider implementing additional controls such as mandatory access controls and file integrity monitoring solutions. The vulnerability demonstrates the importance of input validation in web services and aligns with ATT&CK technique T1059 for command and scripting interpreter and T1078 for valid accounts, as it leverages legitimate authenticated access to escalate privileges through file system manipulation.
The broader implications of this vulnerability highlight the critical need for comprehensive input validation across all network services, particularly those handling user-provided configuration data. Organizations should adopt defense-in-depth strategies that include regular security assessments, proper access control implementation, and continuous monitoring of system configurations. This vulnerability serves as a reminder of the importance of applying security patches promptly and maintaining up-to-date system configurations to prevent exploitation of known weaknesses. The attack vector demonstrates how seemingly minor input validation flaws can lead to significant system compromise when combined with legitimate administrative access, emphasizing the need for robust security controls throughout the entire system lifecycle.