CVE-2020-7454 in FreeBSD
Summary
by MITRE
In FreeBSD 12.1-STABLE before r360971, 12.1-RELEASE before p5, 11.4-STABLE before r360971, 11.4-BETA1 before p1 and 11.3-RELEASE before p9, libalias does not properly validate packet length resulting in modules causing an out of bounds read/write condition if no checking was built into the module.
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Analysis
by VulDB Data Team • 10/18/2020
The vulnerability identified as CVE-2020-7454 affects FreeBSD operating systems across multiple versions including 12.1-STABLE before r360971, 12.1-RELEASE before p5, 11.4-STABLE before r360971, 11.4-BETA1 before p1, and 11.3-RELEASE before p9. This issue resides within the libalias library which serves as a network address translation and packet filtering module. The flaw represents a critical validation failure that impacts the core networking functionality of these FreeBSD systems. The vulnerability stems from insufficient input validation mechanisms within the packet processing routines, creating a scenario where malformed network packets can trigger memory access violations.
The technical implementation of this vulnerability involves the libalias module's failure to properly validate packet length parameters during network packet processing. When network traffic flows through the system, the libalias library processes packets to handle NAT operations and packet filtering. However, due to inadequate bounds checking, the system attempts to read or write data beyond the allocated memory boundaries when encountering packets with unexpected length values. This condition creates an out-of-bounds read/write scenario that can be exploited by malicious actors to manipulate memory contents or cause system instability. The vulnerability operates at the kernel level where network packet processing occurs, making it particularly dangerous as it can affect the entire system's memory management and stability.
The operational impact of CVE-2020-7454 extends beyond simple system crashes or memory corruption. An attacker could potentially leverage this vulnerability to execute arbitrary code within the kernel space, leading to complete system compromise. The out-of-bounds memory access conditions can result in unpredictable behavior including system crashes, data corruption, or privilege escalation. Since libalias is integral to network functionality, systems running affected FreeBSD versions are vulnerable to attacks targeting network traffic processing, making this particularly concerning for servers and network infrastructure. The vulnerability affects systems that utilize network address translation or packet filtering capabilities, which are common in enterprise environments and network appliances.
Mitigation strategies for CVE-2020-7454 focus primarily on applying the official FreeBSD security patches that address the packet validation issues in libalias. System administrators should immediately update to the patched versions of FreeBSD including releases after the mentioned revision numbers. Organizations should also implement network monitoring to detect unusual packet patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-129 Input Validation and CWE-787 Out-of-bounds Write categories, representing both insufficient validation and memory safety issues. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as it enables attackers to potentially gain elevated privileges through kernel-level memory corruption. Additionally, network defenders should consider implementing network segmentation and firewall rules to limit exposure to potentially malicious traffic that could trigger this vulnerability.