CVE-2017-17712 in Linux
Summary
by MITRE
The raw_sendmsg() function in net/ipv4/raw.c in the Linux kernel through 4.14.6 has a race condition in inet->hdrincl that leads to uninitialized stack pointer usage; this allows a local user to execute code and gain privileges.
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Analysis
by VulDB Data Team • 01/18/2023
The vulnerability identified as CVE-2017-17712 represents a critical race condition flaw within the Linux kernel's raw socket implementation that exists in versions through 4.14.6. This issue resides in the raw_sendmsg() function located in net/ipv4/raw.c, where the improper handling of the inet->hdrincl parameter creates a window of opportunity for malicious exploitation. The race condition specifically manifests when multiple threads or processes attempt to access the hdrincl field simultaneously, leading to unpredictable behavior and potential memory corruption. This vulnerability falls under the CWE-362 category of Concurrent Execution using Shared Resource with Unprotected Race Condition, which directly aligns with the fundamental security principle that shared resources must be properly synchronized to prevent concurrent access issues.
The technical exploitation of this vulnerability occurs through a local user who can manipulate the raw socket interface to trigger the race condition in the inet->hdrincl field. When the kernel processes raw socket messages, it relies on the hdrincl flag to determine whether to include IP headers in the packet transmission. The race condition arises because the kernel does not properly synchronize access to this field during concurrent socket operations, allowing an attacker to potentially corrupt the stack memory or manipulate the execution flow. The uninitialized stack pointer usage that results from this race condition creates an environment where arbitrary code execution becomes possible, as the corrupted memory can be leveraged to redirect program execution or manipulate kernel memory structures.
The operational impact of CVE-2017-17712 extends beyond simple privilege escalation to potentially allow full system compromise from a local attacker position. This vulnerability directly maps to the ATT&CK technique T1068 which involves privilege escalation through local exploitation of kernel vulnerabilities. The local user can leverage this flaw to execute code with kernel-level privileges, effectively bypassing user-space security controls and gaining complete control over the affected system. Once exploited, the attacker can perform actions such as installing persistent backdoors, modifying system files, accessing sensitive data, or establishing further network access points. The vulnerability's impact is particularly severe because it does not require network access or external attack vectors, making it exploitable even in isolated or air-gapped environments.
Mitigation strategies for this vulnerability primarily involve applying the official kernel patches released by the Linux kernel development team, which address the race condition through proper synchronization mechanisms. The recommended approach includes upgrading to Linux kernel version 4.14.7 or later, where the race condition has been resolved through proper locking mechanisms around the inet->hdrincl field access. Additionally, system administrators should implement least privilege principles and restrict local user access to raw socket operations where possible. Security monitoring should include detection of suspicious raw socket usage patterns and unusual network activity that might indicate exploitation attempts. Organizations should also consider implementing kernel hardening measures such as stack canaries and address space layout randomization to further complicate exploitation attempts. The vulnerability's classification under the MITRE ATT&CK framework as a local privilege escalation vector emphasizes the importance of maintaining up-to-date kernel versions and implementing comprehensive endpoint protection measures to prevent unauthorized local access to systems.