CVE-2023-32324 - OpenPrinting CUPS Heap Buffer Overflow Vulnerability Leads to Denial of Service Attacks

OpenPrinting's Common Unix Printing System (CUPS) is a widely used open-source printing system for Unix-based platforms. However, in its 2.4.2 and earlier versions, there exists a serious heap buffer overflow vulnerability that could potentially enable remote attackers to execute a denial of service (DoS) attack on the targeted system. This vulnerability in the format_log_line function is the primary means through which an attacker could cause a DoS.

It's important to note that the exploitation of this vulnerability is only feasible when the configuration file cupsd.conf sets the value of loglevel to DEBUG. As of the time of publication, there are no known patches or workarounds available for this issue.

Below is a sample code snippet demonstrating the vulnerable format_log_line function

// Vulnerable format_log_line function
void format_log_line(cupsd_log_message_t *msg, char *buffer, int bufsize)
{
  const char *loglevels[] = {"DEBUG:", "DEBUG2:", "INFO:", "WARN:", "ERROR:", "FATAL:"};
  
  snprintf(buffer, bufsize, "%s %s [Job %d] %s", cupsdGetDateTime(msg->timestamp), loglevels[msg->loglevel], msg->job_id, msg->message);
}

As seen in the above code snippet, it shows that insufficient buffer size validation can lead to a buffer overflow vulnerability. This issue was first documented in the original reference CVE report which provides in-depth details about the vulnerability.

Exploit Details

For a successful DoS attack, the attacker must first exploit the buffer overflow vulnerability in the format_log_line function when the loglevel is set to DEBUG in the cupsd.conf file. An attacker could potentially craft a sequence of log messages that could trigger the overflow, resulting in a crash or unexpected behavior in the CUPS system.

As of now, there are no known patches or workarounds available for CVE-2023-32324. Users of CUPS 2.4.2 and earlier versions are advised to closely monitor the OpenPrinting CUPS GitHub page and the CUPS official announcement page for updates regarding this issue.

In conclusion, the heap buffer overflow vulnerability found in OpenPrinting CUPS 2.4.2 and earlier versions could potentially expose many Unix-based platforms to remote DoS attacks. As there are no known solutions at the time of publication, users should keep an eye on official communication channels for updates and patches to address this issue. In the meantime, avoid setting the loglevel to DEBUG in the cupsd.conf configuration file if possible.

Timeline

Published on: 06/01/2023 17:15:00 UTC
Last modified on: 06/08/2023 14:32:00 UTC