Linux kernel affected by a local privilege escalation vulnerability

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Cisco issued a security advisory on a local privilege escalation vulnerability in the Linux Kernel, patch it as soon as possible.

On Friday, Cisco issued a security advisory on a local privilege escalation vulnerability in the Advanced Linux Sound Architecture (ALSA).

The vulnerability in the Linux Kernel, tracked as CVE-2017-15265, is due to a use-after-free memory error in the ALSA sequencer interface, an attacker could exploit it by running a crafted application on a vulnerable system.

“A vulnerability in the Linux Kernel could allow a local attacker to gain elevated privileges on a targeted system.” reads the Cisco security advisory.

“The vulnerability is due to a use-after-free memory error in the ALSA sequencer interface of the affected application. An attacker could exploit this vulnerability by running a crafted application on a targeted system. A successful exploit could allow the attacker to gain elevated privileges on the targeted system.”

According to a discussion at SUSE’s Bugzilla, a patch for the Linux Kernel vulnerability was added to the ALSA git tree on October 11, .

“We may fix this in a few different ways, and in this patch, it’s fixed simply by taking the refcount properly at snd_seq_create_port() and letting the caller unref the object after use.” states the description on the ALSA git tree.

The use-after-free is triggered by a bug in snd_seq_create_port() as explained in the advisory:

“There is a potential race window opened at creating and deleting a port via ioctl, as spotted by fuzzing. snd_seq_create_port() creates a port object and returns its pointer, but it doesn’t take the refcount, thus it can be deleted immediately by another thread. Meanwhile, snd_seq_ioctl_create_port() still calls the function snd_seq_system_client_ev_port_start() with the created port object that is being deleted, and this triggers use-after-free” continues the description.

privilege escalation Linux Kernel

Kernel.org has confirmed the vulnerability, the good news is that to exploit this vulnerability, the attacker must have local access to the targeted system, a circumstance that drastically reduces the likelihood of a successful exploit.

Source:http://securityaffairs.co/wordpress/64356/hacking/linux-privilege-escalation.html

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