CVE-2015-3693 in Mac OS X
Summary
by MITRE
Apple Mac EFI before 2015-001, as used in OS X before 10.10.4 and other products, does not properly set refresh rates for DDR3 RAM, which might make it easier for remote attackers to conduct row-hammer attacks, and consequently gain privileges or cause a denial of service (memory corruption), by triggering certain patterns of access to memory locations.
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Analysis
by VulDB Data Team • 12/05/2024
The vulnerability identified as CVE-2015-3693 represents a critical flaw in Apple Mac EFI firmware versions prior to 2015-001, affecting OS X systems before version 10.10.4 and various other Apple products. This security weakness stems from improper configuration of DDR3 RAM refresh rates within the Extensible Firmware Interface implementation, creating exploitable conditions that significantly impact system security and stability. The flaw exists at the firmware level, specifically within the EFI implementation that manages hardware initialization and memory configuration during system boot processes, making it a foundational security concern that affects the entire system architecture.
The technical nature of this vulnerability lies in the improper handling of memory refresh operations within the EFI firmware environment, where DDR3 RAM refresh rates are not correctly configured during system initialization. This misconfiguration creates predictable memory access patterns that enable attackers to exploit row-hammer vulnerabilities, a class of memory errors that occur when repeated row activations cause bit flips in adjacent memory rows. The vulnerability specifically impacts the timing and frequency of memory refresh operations, which are critical for maintaining data integrity in dynamic random-access memory systems. When refresh rates are improperly set, certain memory access patterns can trigger the row-hammer phenomenon, leading to unintended data corruption and potential privilege escalation opportunities.
The operational impact of this vulnerability extends beyond simple memory corruption, creating conditions that allow remote attackers to execute sophisticated attacks against affected systems. Attackers can leverage the improper memory refresh configuration to trigger specific access patterns that induce row-hammer effects, potentially leading to privilege escalation attacks that could compromise system integrity and allow unauthorized access to sensitive system resources. Additionally, the vulnerability can result in denial of service conditions through memory corruption that destabilizes system operations, making affected systems unreliable and potentially unusable. The remote exploitability aspect means that attackers do not require physical access to the target system, making this vulnerability particularly concerning for enterprise environments and systems with network connectivity.
This vulnerability aligns with CWE-119, which addresses "Improper Access of Resource During Just-in-Time Allocation," and relates to ATT&CK technique T1068, "Exploitation for Privilege Escalation," as the flaw enables attackers to gain elevated system privileges through memory manipulation techniques. The weakness also connects to ATT&CK technique T1499, "Endpoint Denial of Service," due to the potential for causing system instability through memory corruption. Mitigation strategies should focus on firmware updates to address the improper DDR3 refresh rate configuration, along with implementing memory access pattern monitoring and validation mechanisms. System administrators should prioritize applying Apple's firmware updates and security patches, while also considering additional protective measures such as memory integrity checking and monitoring for anomalous access patterns that could indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper firmware implementation and the need for comprehensive security testing at all system levels, including the foundational firmware components that interface directly with hardware memory controllers.