Computer security is an ever-growing field that is constantly being challenged by new vulnerabilities and exploits. In this article, we will take a deep dive into a recently discovered vulnerability, CVE-2024-42333, which allows an attacker to leak a small amount of Zabbix Server memory. Our focus will be on understanding the exploit details, the code involved, and taking a closer look at the original references to better comprehend its implications.
Context
Before we dive into the vulnerability details, let's take a moment to understand what Zabbix is and its purpose. Zabbix is an open-source monitoring tool that helps many organizations monitor their IT infrastructure, including servers, networks, and applications. The Zabbix Server is a core component of this infrastructure monitoring solution, allowing for data collection, processing, and storage.
Original References
The vulnerability we're investigating today, CVE-2024-42333, was discovered by an independent security researcher who had published the details in the Zabbix GitHub repository (https://github.com/zabbix/zabbix/ The researcher demonstrated that it is possible to leak small amounts of Zabbix Server information through an out of bounds read vulnerability. The affected file is located in the src/libs/zbxmedia/email.c, which handles the process of sending email notifications to users.
Exploit Details
Let's now dig into the vulnerability details. The issue is due to improper processing of email notifications sent when an alert is triggered. The attacker can craft a malicious payload and embed it within the Zabbix Server configuration. When this payload is processed, the server would read the data out of bounds from the email.c file, causing a memory leak.
Below is a snippet of the vulnerable code located in the email.c file
static int parse_email_address(char **addr, char *addr_loc, size_t addr_loc_len, char *error, size_t max_error_len)
{
int ret = FAIL;
char *at = strchr(addr_loc, '@'), *domain_start, *p;
zbx_skip_utf8_rfc_3696_sequences;
if (NULL == at)
{
zbx_snprintf(error, max_error_len, "cannot find separator '@' in address \"%s\"", addr_loc);
goto out;
}
domain_start = at + 1;
if ('\' == *domain_start)
{
zbx_snprintf(error, max_error_len, "domain is empty in address \"%s\"", addr_loc);
goto out;
}
*addr = addr_loc;
ret = SUCCEED;
out:
return ret;
}
The issue stems from the improper parsing of email addresses due to the lack of proper bounds checking. The function parse_email_address() accepts a user-supplied email address as input, as seen in the code above. The server processes this email address, but when it encounters the '@' character, it proceeds to read the contents beyond the allowed bounds without any proper checks in place.
Mitigation
The Zabbix development team has acknowledged the vulnerability and has taken steps to resolve it. The recommended approach is to keep your Zabbix Server updated to the latest version, which contains the necessary security patches. Users should follow the official Zabbix documentation for guidance on updating their installations (https://www.zabbix.com/documentation/current/manual/installation/upgrade).
Conclusion
In conclusion, CVE-2024-42333 is a critical vulnerability that has the potential to leak sensitive information from your Zabbix Server. While the exploit itself may not lead to a full compromise of the server, leaking any amount of data is concerning, especially when considering the infrastructure that Zabbix monitors. Always ensure that your software is up-to-date and follow best practices to avoid falling victim to associated attacks.
Timeline
Published on: 11/27/2024 12:15:21 UTC