CVE-2016-8658 in Linux
Summary
by MITRE
Stack-based buffer overflow in the brcmf_cfg80211_start_ap function in drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c in the Linux kernel before 4.7.5 allows local users to cause a denial of service (system crash) or possibly have unspecified other impact via a long SSID Information Element in a command to a Netlink socket.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 09/26/2022
The vulnerability identified as CVE-2016-8658 represents a critical stack-based buffer overflow affecting the Linux kernel's wireless subsystem, specifically within the brcmf_cfg80211_start_ap function. This flaw exists in the Broadcom brcm80211 wireless driver implementation and impacts kernel versions prior to 4.7.5, making it a significant concern for systems utilizing Broadcom wireless hardware. The vulnerability arises from inadequate input validation when processing wireless network configuration commands, particularly those involving the SSID Information Element that is part of the 802.11 management frames. The flaw manifests when a local user crafts a malicious Netlink socket command containing an excessively long SSID value, which then gets processed without proper bounds checking in the kernel space.
The technical implementation of this vulnerability stems from improper handling of user-supplied data within kernel memory structures. When the brcmf_cfg80211_start_ap function processes wireless network configuration requests, it fails to validate the length of the SSID Information Element before copying it into a fixed-size stack buffer. This classic buffer overflow condition allows an attacker to overwrite adjacent stack memory locations, potentially corrupting critical kernel data structures or executing arbitrary code. The vulnerability operates at the kernel level, meaning that successful exploitation could lead to complete system compromise, though the initial impact is typically limited to denial of service conditions. The use of Netlink sockets as the attack vector makes this vulnerability particularly concerning because these are standard kernel communication interfaces used by network management applications and wireless configuration tools.
From an operational perspective, this vulnerability presents a significant risk to wireless network infrastructure and endpoint security. Local users with access to the system can exploit this flaw to trigger system crashes, leading to denial of service conditions that can disrupt wireless connectivity and potentially affect system availability. While the primary impact is denial of service, the potential for unspecified other impacts cannot be ruled out, suggesting that sophisticated exploitation might enable privilege escalation or information disclosure. The vulnerability affects systems using Broadcom wireless hardware, which is prevalent in many enterprise and consumer devices, making the attack surface quite broad. Network administrators should be particularly concerned about systems where local user access is not properly restricted, as this vulnerability can be exploited by any user with access to the system's command line or wireless configuration interfaces.
Mitigation strategies for CVE-2016-8658 primarily focus on kernel version updates and access control measures. The most effective immediate solution involves upgrading the Linux kernel to version 4.7.5 or later, where the buffer overflow has been patched through proper bounds checking and input validation. System administrators should also implement strict access controls to limit local user privileges, particularly for wireless configuration interfaces and Netlink socket access. Additional defensive measures include monitoring for unusual wireless configuration activities and implementing network segmentation to limit the potential impact of exploitation. Organizations should also consider deploying kernel hardening techniques such as stack canaries, address space layout randomization, and kernel module signing to reduce the effectiveness of potential exploitation attempts. This vulnerability aligns with CWE-121 Stack-based Buffer Overflow and can be categorized under ATT&CK technique T1068, Local Privilege Escalation, and T1489, Service Stop, when considering the denial of service impact and potential privilege escalation paths.