Signal Handler Race Condition Vulnerability in OpenSSH sshd

What is CVE-2024-6409?

CVE-2024-6409 is a significant vulnerability identified in OpenSSH's server component, known as sshd, which is widely used for secure remote access and communication in various operating systems. This vulnerability arises from a race condition in the way that signals are handled by the sshd service. If exploited, it could allow an unauthenticated remote attacker to execute arbitrary code on the server, posing a severe threat to the integrity and confidentiality of data and potentially compromising the entire server environment.

Technical Details

The vulnerability is rooted in the asynchronous handling of the SIGALRM signal within the sshd process. When a remote user fails to authenticate within a predefined time frame, the SIGALRM handler is triggered. Unfortunately, the functions invoked by this signal handler are not designated as async-signal-safe. This creates a window of opportunity for attackers to manipulate the execution flow of the sshd process. The failure to ensure that signal handling procedures are safe can lead to unpredictable behavior and can be exploited to achieve remote code execution under the context of the unprivileged user running sshd.

Impact of the Vulnerability

1. Remote Code Execution: The primary consequence of this vulnerability is the potential for an attacker to execute arbitrary code on the affected system as an unprivileged user. This could lead to unauthorized actions on the server and compromise sensitive data.

2. System Compromise: Exploitation of CVE-2024-6409 could allow attackers to gain control over the server, possibly leading to further exploitation pathways. This could facilitate lateral movement within networks, elevating privileges, or deploying additional malware.

3. Data Breach Risks: The implications of an unauthorized code execution are serious, as it might result in exposure or theft of sensitive information stored on the server. A breach could incur significant financial and reputational damage to organizations relying on the affected OpenSSH services.

News Articles

Trend Micro

CVE-2024-6409

The Potential Impact of the OpenSSH Vulnerabilities CVE-2024–6387 and CVE-2024-6409

We take a look at the OpenSSH vulnerabilities CVE-2024–6387 and CVE-2024-6409, examining their potential real-world impact and the possibility of exploitation for CVE-2024–6387 in x64 systems.

5 months ago

Trend Micro

CVE-2024-6409

The Potential Impact of the OpenSSH Vulnerabilities CVE-2024–6387 and CVE-2024-6409

We take a look at the OpenSSH vulnerabilities CVE-2024–6387 and CVE-2024-6409, examining their potential real-world impact and the possibility of exploitation for CVE-2024–6387 in x64 systems.

5 months ago

Trend Micro

CVE-2024-6409

The Potential Impact of the OpenSSH Vulnerabilities CVE-2024–6387 and CVE-2024-6409

We take a look at the OpenSSH vulnerabilities CVE-2024–6387 and CVE-2024-6409, examining their potential real-world impact and the possibility of exploitation for CVE-2024–6387 in x64 systems.

5 months ago

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