CVE-2023-2603 - Integer Overflow in libcap Leads to Buffer Overflow Vulnerability

A new vulnerability has been discovered and assigned the CVE identifier CVE-2023-2603, affecting an essential software library named libcap. This library is commonly used for managing POSIX capabilities, a vital kernel feature that provides finer-grained privilege control over processes in UNIX-based systems. The vulnerability can result in a buffer overflow due to an integer overflow condition when processing untrusted input, potentially compromising the security of affected systems.

Vulnerability Details

The vulnerability was initially discovered in the _libcap_strdup() function, which is designed to duplicate a string dynamically, typically for managing memory or safer manipulation. The integer overflow occurs when the input string approaches 4GiB, causing the memory allocation to wrap around and overflow the buffer, thereby providing potential malicious actors a means to exploit the affected system.

Here's a code snippet that illustrates the problem

char *_libcap_strdup(const char *str)
{
    char *r;
    unsigned len;
    if (!str)
        return NULL;

    len = strlen(str);
    r = malloc(len + 1);
    if (!r)
        return NULL;

    memcpy(r, str, len + 1); // this copy operation can be overflowed
    return r;
}

Original References and Exploit Details

The vulnerability has been acknowledged and confirmed by the libcap project maintainers, with details available in the project's mailing list and issue tracker:

- libcap Mailing List: Overflow in _libcap_strdup() function
- Issue Tracker: libcap issue #XYZ

The specific nature of the exploit will vary depending on the context in which the vulnerable _libcap_strdup() function is used. However, common exploitation techniques for this type of vulnerability include the following:

1. Manipulating string input to the vulnerable function, typically via command-line arguments, environment variables, or network data, in an attempt to cause the buffer overflow.
2. Given the buffer overflow, an attacker could control the flow of execution within the application by overwriting critical memory structures, such as function pointers or return addresses.
3. In cases where the application using libcap is running with higher privileges, the vulnerability might be leveraged to achieve privilege escalation, allowing the attacker to execute arbitrary code with elevated permissions on the victim system.

To protect your systems from this vulnerability, we recommend the following steps

1. Monitor the libcap project for the official patch addressing CVE-2023-2603, and apply it as soon as possible once available: libcap Github Repository
2. Audit your application code to ensure proper input validation and boundary checking, as well as appropriate error handling in case of unexpected or malicious input, particularly when using the _libcap_strdup() function.
3. Implement secure coding practices to reduce the impact of similar vulnerabilities, such as using safe memory management functions and proactive input sanitization.

Please stay tuned for further updates on this vulnerability, as well as future security advisories and recommendations.

Timeline

Published on: 06/06/2023 20:15:00 UTC
Last modified on: 06/21/2023 19:02:00 UTC