CVE-2018-4249 in iOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 11.4 is affected. macOS before 10.13.5 is affected. tvOS before 11.4 is affected. watchOS before 4.3.1 is affected. The issue involves pktmnglr_ipfilter_input in com.apple.packet-mangler in the "Kernel" component. It allows attackers to execute arbitrary code in a privileged context or cause a denial of service (integer overflow and stack-based buffer overflow) via a crafted app.
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Analysis
by VulDB Data Team • 06/18/2024
The vulnerability identified as CVE-2018-4249 represents a critical security flaw within Apple's kernel-level networking component known as packet-mangler. This issue affects multiple Apple operating systems including iOS versions prior to 11.4, macOS versions before 10.13.5, tvOS versions before 11.4, and watchOS versions before 4.3.1. The vulnerability resides in the pktmnglr_ipfilter_input function within the kernel component, which handles network packet filtering operations. The flaw manifests through two distinct but related attack vectors that together create a severe security risk for affected systems.
The technical implementation of this vulnerability involves an integer overflow condition combined with a stack-based buffer overflow within the packet filtering subsystem. Attackers can exploit this weakness by crafting malicious applications that send specially constructed network packets to the vulnerable system. When the kernel processes these malformed packets through the pktmnglr_ipfilter_input function, the integer overflow corrupts memory management structures, while the subsequent stack-based buffer overflow allows arbitrary code execution. This dual nature of the vulnerability means that attackers can either gain elevated privileges to execute malicious code within the kernel context or cause a system crash leading to denial of service conditions. The integer overflow occurs during packet size calculations where the system fails to properly validate input values, leading to memory corruption that can be exploited to overwrite critical kernel memory areas.
The operational impact of CVE-2018-4249 extends beyond simple exploitation capabilities as it provides attackers with privileged execution rights within the kernel space, effectively bypassing normal system security boundaries. This vulnerability directly violates the principle of least privilege by allowing unprivileged applications to execute code with kernel-level permissions, which could enable attackers to access sensitive system data, modify critical system files, or establish persistent backdoors. The denial of service component of this vulnerability means that even if exploitation fails, attackers can still disrupt system operations by causing kernel crashes and system instability. From an attacker's perspective, this vulnerability aligns with the MITRE ATT&CK framework's privilege escalation techniques, specifically targeting kernel-level access and system integrity. The vulnerability also maps to CWE-190, which describes integer overflow conditions, and CWE-121, which covers stack-based buffer overflow issues, making it a compound vulnerability that leverages multiple exploitation vectors.
Mitigation strategies for CVE-2018-4249 primarily focus on immediate system updates and patch management procedures. Apple released security updates for all affected operating systems that address the integer overflow and buffer overflow conditions in the packet-mangler kernel component. Organizations should prioritize deployment of these patches across all affected Apple devices to eliminate the exploitation risk. Network administrators should also implement additional monitoring measures to detect anomalous packet traffic patterns that might indicate exploitation attempts. The vulnerability's nature suggests that traditional network security measures may not be sufficient, as the attack occurs at the kernel level and can bypass standard application firewalls. System hardening practices including disabling unnecessary network services and restricting application permissions can provide additional defense layers, though these measures do not address the core kernel vulnerability itself. Security teams should also conduct regular vulnerability assessments to ensure that all Apple devices within their environment are properly updated and monitored for similar kernel-level exploits.