CVE-2015-7015 in Mac OS X
Summary
by MITRE
Heap-based buffer overflow in the DNS client library in configd in Apple iOS before 9.1, OS X before 10.11.1, and watchOS before 2.0.1 allows attackers to execute arbitrary code via a crafted app that sends a spoofed configd response to a client.
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Analysis
by VulDB Data Team • 06/24/2022
The vulnerability identified as CVE-2015-7015 represents a critical heap-based buffer overflow within the DNS client library component of Apple's configd service. This flaw exists in multiple Apple operating systems including iOS versions prior to 9.1, macOS versions before 10.11.1, and watchOS versions before 2.0.1. The vulnerability stems from insufficient input validation and memory management within the configd service's handling of DNS responses, creating a condition where malicious actors can manipulate heap memory allocation through specially crafted DNS responses. The technical implementation involves the configd service failing to properly bounds-check data received from DNS queries, allowing an attacker to overwrite adjacent memory locations in the heap. This type of vulnerability falls under CWE-121, heap-based buffer overflow, and represents a classic memory safety issue that enables arbitrary code execution. The attack vector requires a malicious application to send a spoofed configd response to a client, exploiting the trust relationship between the DNS client and the configd service. The operational impact of this vulnerability is severe as it allows remote code execution with the privileges of the configd process, which typically operates with elevated system privileges. Attackers can leverage this vulnerability to gain unauthorized access to system resources, execute malicious payloads, and potentially escalate privileges to full system compromise. The vulnerability aligns with ATT&CK technique T1059.007 for command and script injection, as successful exploitation could enable attackers to execute arbitrary commands within the system context. The heap-based nature of the overflow means that the attacker can manipulate memory layout to redirect execution flow, potentially leading to complete system compromise. This vulnerability is particularly dangerous because it operates at the system level within the network configuration service, making it difficult to detect and exploit without proper network monitoring. The flaw demonstrates a lack of proper memory bounds checking in the DNS response parsing logic, where the configd service does not validate the size of incoming DNS data before copying it into fixed-size buffers. This allows attackers to overflow the allocated heap memory and overwrite critical data structures, function pointers, or return addresses. The vulnerability's exploitation requires careful crafting of DNS responses to ensure the overflow occurs at specific memory locations that can be controlled to redirect program execution. System administrators and security professionals should consider this vulnerability as a high-priority threat due to its potential for privilege escalation and remote code execution capabilities. The affected systems represent a significant attack surface since configd is a core system service that handles network configuration requests from various applications and system components, making the attack impact widespread across different application contexts. The vulnerability also highlights the importance of input validation in system-level services, particularly those handling network communications where malformed data can lead to critical security breaches. Organizations should prioritize patching affected systems to prevent exploitation, as the vulnerability provides attackers with a straightforward path to system compromise through network-based attacks.
The technical characteristics of this vulnerability align with common patterns found in heap overflow exploits, where the attacker manipulates memory layout to achieve code execution. The fact that this affects multiple Apple platforms indicates a systemic issue within the configd implementation that requires comprehensive remediation across all affected operating systems. The vulnerability's classification as heap-based buffer overflow (CWE-121) places it within the category of memory safety issues that are particularly challenging to detect and prevent through traditional runtime protections. From a security operations perspective, this vulnerability demonstrates the critical importance of maintaining up-to-date system patches and monitoring for suspicious network traffic patterns that might indicate exploitation attempts. The exploitability of this vulnerability is enhanced by the fact that it does not require user interaction or specific application privileges to be effective, making it particularly dangerous in enterprise environments where network-based attacks are common. The vulnerability's presence in system-level services like configd also means that exploitation could potentially bypass traditional application sandboxing mechanisms, providing attackers with direct access to core system functionality. This makes the vulnerability particularly concerning from a defense-in-depth perspective, as it represents a failure in multiple layers of system protection, including network filtering, application security, and system integrity controls. The security implications extend beyond immediate code execution to include potential data exfiltration, system reconnaissance, and establishment of persistent access points within affected networks. Organizations should implement network monitoring solutions capable of detecting anomalous DNS traffic patterns that could indicate exploitation attempts, while also ensuring that all systems are updated with the latest security patches to prevent successful exploitation of this vulnerability.