CVE-2019-9502 in wl WiFi Driver
Summary
by MITRE
The Broadcom wl WiFi driver is vulnerable to a heap buffer overflow. If the vendor information element data length is larger than 164 bytes, a heap buffer overflow is triggered in wlc_wpa_plumb_gtk. In the worst case scenario, by sending specially-crafted WiFi packets, a remote, unauthenticated attacker may be able to execute arbitrary code on a vulnerable system. More typically, this vulnerability will result in denial-of-service conditions.
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Analysis
by VulDB Data Team • 03/28/2024
The CVE-2019-9502 vulnerability resides within the Broadcom wl WiFi driver implementation, representing a critical heap buffer overflow condition that fundamentally compromises system integrity. This flaw manifests specifically within the wlc_wpa_plumb_gtk function when processing vendor information element data, where the driver fails to properly validate input lengths before attempting memory operations. The vulnerability occurs when the vendor information element exceeds the expected 164-byte limit, triggering an exploitable buffer overflow in heap-allocated memory structures. This represents a classic software security flaw where insufficient bounds checking enables attackers to overwrite adjacent memory regions, potentially leading to arbitrary code execution or system instability.
The technical exploitation of this vulnerability aligns with CWE-121, which catalogs heap-based buffer overflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1059.007 for command and scripting interpreter execution. The heap buffer overflow in wlc_wpa_plumb_gtk creates a scenario where attacker-controlled data can overwrite critical heap metadata or function pointers, enabling privilege escalation or remote code execution. The vulnerability's remote exploitability means that an unauthenticated attacker can craft malicious WiFi packets containing oversized vendor information elements, sending them to vulnerable systems without requiring any prior authentication or access privileges. This makes the flaw particularly dangerous in wireless network environments where attackers can operate from considerable distances.
The operational impact of CVE-2019-9502 extends beyond simple exploitation scenarios to encompass widespread denial-of-service conditions that can disrupt network connectivity and system availability. In typical exploitation cases, the buffer overflow will likely cause the WiFi driver to crash or become unresponsive, leading to complete network disconnection for affected devices. However, under specific conditions and with sufficient knowledge of the target system's memory layout, attackers could potentially leverage this vulnerability to execute arbitrary code with kernel-level privileges, effectively compromising the entire system. The vulnerability affects numerous devices including routers, access points, and end-user devices that utilize Broadcom WiFi chipsets, making it a significant concern for enterprise and consumer networks alike.
Mitigation strategies for this vulnerability require immediate patching of affected systems with updated Broadcom driver releases that include proper bounds checking for vendor information element data. Network administrators should implement network segmentation and monitoring to detect anomalous WiFi traffic patterns that might indicate exploitation attempts. Additionally, disabling unnecessary WiFi features and implementing robust firewall rules can reduce the attack surface. Organizations should conduct comprehensive vulnerability assessments to identify all systems running affected Broadcom WiFi drivers and prioritize remediation efforts based on risk exposure. The vulnerability also highlights the importance of secure coding practices in network driver development, emphasizing the need for rigorous input validation and memory management procedures to prevent similar heap-based buffer overflow conditions from occurring in future implementations.