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OpenSSH Releases Patch for New Pre-Auth Double Free Vulnerability
The maintainers of OpenSSH have released OpenSSH 9.2 to address a number of security bugs, including a memory safety vulnerability in the OpenSSH server (sshd). Tracked as CVE-2023-25136, the shortcoming has been classified as a pre-authentication double free vulnerability that was introduced in version 9.1. "This is not believed to be exploitable, and it occurs in the unprivileged pre-auth
Authentication / Vulnerability
The maintainers of OpenSSH have released OpenSSH 9.2 to address a number of security bugs, including a memory safety vulnerability in the OpenSSH server (sshd).
Tracked as CVE-2023-25136, the shortcoming has been classified as a pre-authentication double free vulnerability that was introduced in version 9.1.
“This is not believed to be exploitable, and it occurs in the unprivileged pre-auth process that is subject to chroot(2) and is further sandboxed on most major platforms,” OpenSSH disclosed in its release notes on February 2, 2023.
Credited with reporting the flaw to OpenSSH in July 2022 is security researcher Mantas Mikulenas.
OpenSSH is the open source implementation of the secure shell (SSH) protocol that offers a suite of services for encrypted communications over an unsecured network in a client-server architecture.
“The exposure occurs in the chunk of memory freed twice, the 'options.kex_algorithms,’” Qualys researcher Saeed Abbasi said, adding the issue results in a “double free in the unprivileged sshd process.”
Double free flaws arise when a vulnerable piece of code calls the free() function – which is used to deallocate memory blocks – twice, leading to memory corruption, which, in turn, could lead to a crash or execution of arbitrary code.
“Doubly freeing memory may result in a write-what-where condition, allowing an attacker to execute arbitrary code,” MITRE notes in its description of the flaw.
“While the double-free vulnerability in OpenSSH version 9.1 may raise concerns, it is essential to note that exploiting this issue is no simple task,” Abbasi explained.
“This is due to the protective measures put in place by modern memory allocators and the robust privilege separation and sandboxing implemented in the impacted sshd process.”
Users are recommended to update to OpenSSH 9.2 to mitigate potential security threats.
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Details have emerged about a now-patched flaw in OpenSSH that could be potentially exploited to run arbitrary commands remotely on compromised hosts under specific conditions. "This vulnerability allows a remote attacker to potentially execute arbitrary commands on vulnerable OpenSSH's forwarded ssh-agent," Saeed Abbasi, manager of vulnerability research at Qualys, said in an analysis last week.
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Categories: Exploits and vulnerabilities Categories: News Tags: patch Tuesday Tags: Microsoft Tags: Apple Tags: Adobe Tags: SAP Tags: Citrix Tags: Cisco Tags: Atlassian Tags: Google Tags: Mozilla Tags: Forta Tags: OpenSSH Tags: CVE-2023-21823 Tags: CVE-2023-21715 Tags: OneNote Tags: CVE-2023-23376 Tags: CVE-2023-21706 Tags: CVE-2023-21707 Tags: CVE-2023-21529 Tags: CVE-2023-21716 Tags: CVE-2023-23378 Tags: CVE-2023-22501 Tags: CVE-2023-24486 Tags: CVE-2023-24484 Tags: CVE-2023-24484 Tags: CVE-2023-24483 Tags: CVE-2023-25136 Tags: GoAnywhere Microsoft has released updates to patch three zero-days and lots of other vulnerabilities and so have several other vendors (Read more...) The post Update now! February's Patch Tuesday tackles three zero-days appeared first on Malwarebytes Labs.
OpenSSH server (sshd) 9.1 introduced a double-free vulnerability during options.kex_algorithms handling. This is fixed in OpenSSH 9.2. The double free can be triggered by an unauthenticated attacker in the default configuration; however, the vulnerability discoverer reports that "exploiting this vulnerability will not be easy."