CVE-2017-17052 in Linux
Summary
by MITRE • 01/25/2023
The mm_init function in kernel/fork.c in the Linux kernel before 4.12.10 does not clear the ->exe_file member of a new process's mm_struct, allowing a local attacker to achieve a use-after-free or possibly have unspecified other impact by running a specially crafted program.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2017-17052 resides within the Linux kernel's memory management subsystem, specifically in the mm_init function located in kernel/fork.c. This flaw affects Linux kernel versions prior to 4.12.10 and represents a critical security issue that enables local privilege escalation through improper memory handling during process creation. The vulnerability stems from the failure to properly initialize the ->exe_file member of a new process's memory management structure, creating a dangerous condition that can be exploited by malicious local users.
The technical implementation of this vulnerability involves the improper initialization of memory management structures during process forking operations. When a new process is created through fork() system calls, the kernel allocates a new memory management structure (mm_struct) for the child process. However, the mm_init function fails to clear the ->exe_file member pointer, which previously pointed to a valid executable file object in the parent process. This oversight creates a scenario where the child process inherits a dangling pointer to the parent's executable file object, leading to potential use-after-free conditions when the original executable file object is freed but the child process continues to reference it.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can potentially enable local attackers to achieve privilege escalation or execute arbitrary code within the context of the target process. The inherited ->exe_file pointer can be manipulated to point to maliciously crafted objects, creating opportunities for attackers to exploit the use-after-free condition to gain elevated privileges or cause system instability. This vulnerability directly relates to CWE-415: Double Free and CWE-416: Use After Free, both of which are fundamental memory safety issues that have historically led to significant security breaches in operating systems. The attack vector requires local system access, making it particularly concerning for environments where untrusted users have login privileges.
From an adversarial perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under T1068: Exploitation for Privilege Escalation, where attackers leverage kernel-level flaws to gain elevated system privileges. The vulnerability can be exploited through carefully crafted programs that trigger the specific memory management path, potentially allowing attackers to manipulate the inherited ->exe_file pointer to point to controlled memory regions. The exploitation process typically involves creating a scenario where the original executable file object is freed while the child process maintains a reference to it, enabling subsequent memory corruption attacks that can be leveraged for privilege escalation or code execution. System administrators should prioritize patching affected kernel versions to prevent exploitation, as the vulnerability provides a direct path to local privilege escalation that can ultimately compromise the entire system. The recommended mitigation involves upgrading to Linux kernel version 4.12.10 or later, where the improper initialization of the ->exe_file member has been corrected to prevent the inheritance of dangling pointers during process creation.