CVE-2017-9075 in Linux
Summary
by MITRE
The sctp_v6_create_accept_sk function in net/sctp/ipv6.c in the Linux kernel through 4.11.1 mishandles inheritance, which allows local users to cause a denial of service or possibly have unspecified other impact via crafted system calls, a related issue to CVE-2017-8890.
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Analysis
by VulDB Data Team • 12/06/2022
The vulnerability identified as CVE-2017-9075 resides within the Linux kernel's SCTP (Stream Control Transmission Protocol) implementation, specifically in the sctp_v6_create_accept_sk function located in net/sctp/ipv6.c. This flaw represents a critical inheritance handling issue that affects kernel versions through 4.11.1, creating a significant security risk for systems utilizing SCTP networking protocols. The vulnerability is particularly concerning as it allows local attackers to manipulate system calls in a manner that can lead to system instability or potentially more severe consequences.
The technical flaw stems from improper handling of socket inheritance mechanisms within the SCTP IPv6 implementation. When the sctp_v6_create_accept_sk function processes socket creation and acceptance operations, it fails to correctly manage the inheritance of socket parameters and states from parent to child sockets. This inheritance mishandling creates a condition where crafted system calls can exploit the improper state management, leading to memory corruption or resource exhaustion. The vulnerability is classified under CWE-367, which deals with Time-of-Check to Time-of-Use (TOCTOU) flaws, as the improper inheritance creates a window where socket states can be manipulated between checks and actual operations.
From an operational perspective, this vulnerability presents a substantial risk to system availability and stability. Local users can leverage this flaw to trigger a denial of service condition that may result in system crashes, kernel panics, or complete system lockups. The impact extends beyond simple denial of service as the vulnerability may enable privilege escalation or other unspecified security consequences, making it particularly dangerous in multi-user environments or systems where local access is possible. The related nature to CVE-2017-8890 indicates this represents part of a broader class of inheritance-related vulnerabilities within the kernel's networking stack.
The attack surface for this vulnerability is primarily limited to local users who have the ability to make system calls to the kernel's SCTP implementation, which typically requires either direct system access or the ability to execute code with sufficient privileges to trigger the vulnerable code path. Systems running affected kernel versions and utilizing SCTP networking protocols are at risk, particularly those in server environments or applications that rely heavily on SCTP for communication. The vulnerability aligns with ATT&CK technique T1068, which involves exploiting local system privileges to escalate access or cause system instability.
Mitigation strategies for CVE-2017-9075 include immediate kernel updates to versions that contain the patched SCTP implementation, which addresses the inheritance handling issues in the sctp_v6_create_accept_sk function. System administrators should also consider implementing network segmentation to limit local access to systems running vulnerable kernels, and monitoring for unusual system behavior or denial of service patterns that might indicate exploitation attempts. Additionally, disabling SCTP support entirely on systems where it is not required provides a complete workaround for this vulnerability. The fix implemented in patched versions addresses the core inheritance mechanism by ensuring proper state management and validation during socket creation and acceptance operations, preventing the manipulation that leads to the denial of service conditions.