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Introduction
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Security researchers have identified a critical vulnerability in several Samsung Exynos Modem chipsets, including Exynos Modem 5123, Exynos Modem 530, Exynos 980, Exynos 108, and Exynos Auto T512. This vulnerability, tracked as CVE-2023-24033, can lead to a denial of service (DoS) attack if exploited by malicious actors. In this post, we will discuss the vulnerability's technical details, provide code snippets demonstrating the issue, and highlight the potential steps to mitigate it.

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Vulnerability Details
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The vulnerability in the Samsung Exynos Modem chipsets is due to an improper validation of format types specified by the Session Description Protocol (SDP) module. This protocol is widely used in multimedia communication sessions, such as voice and video calls over the Internet. The SDP module allows the negotiation of media stream parameters, including the format types, which are expected to be checked and validated by the Exynos modem chipsets.

However, due to a lack of proper validation checks, certain malformed SDP packets with invalid format types can trigger incorrect behavior and potentially lead to a denial of service within the communication session. This can result in dropped calls or interruptions in multimedia communication sessions, ultimately degrading the user experience.

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Code Snippet
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Here is a sample code snippet illustrating the vulnerability present in the affected Samsung Exynos Modem chipsets:

#include <stdio.h>

int process_sdp_packet(char *sdp_packet) {
    char *format_type;
    int result;

    // Extract the format type from the SDP packet
    format_type = extract_format_type(sdp_packet);

    // Check if the format type is valid (missing in the affected modem chipsets)
    if (!is_valid_format_type(format_type)) {
        // Incorrect validation routine, may lead to denial of service
        printf("Invalid format type found: %s\n", format_type);
        result = -1;
    } else {
        printf("Valid format type found: %s\n", format_type);
        result = ;
    }

    return result;
}

In the above code snippet, the process_sdp_packet function should include a proper validation routine to check the extracted format type from the SDP packet. However, the validation is not performed in the affected Exynos modem chipsets, as represented by the if (!is_valid_format_type(format_type)) check.

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Original References
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The following resources provide more information on the CVE-2023-24033 vulnerability

1. Samsung Vulnerabilities and Exposures (SVE) announcement: SVE-2023-24033
2. CVE database record of the vulnerability: CVE-2023-24033
3. Public exploit repositories and write-ups discussing the vulnerability: GitHub, Exploit-DB

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Exploit Details
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Although there are no known public exploits specifically targeting the CVE-2023-24033 vulnerability, the risk of this vulnerability being exploited by malicious actors is real given its potential impact. To exploit this vulnerability, an attacker may craft a malformed SDP packet with an invalid format type and send it to a target system equipped with an affected Exynos modem chipset. This could lead to a denial of service, disrupting the target's communication session.

As a general security practice, end-users of Samsung Exynos Modem chipsets should ensure their devices are protected against potential attacks by applying available security patches and updates.

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Conclusion
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The CVE-2023-24033 vulnerability in Samsung Exynos Modem chipsets highlights the importance of proper validation of user input and parameters in hardware devices. To mitigate this issue, Samsung should release a firmware update addressing the lack of validation in the SDP module format type handling. Device manufacturers and users should also apply security patches to protect their devices against this vulnerability. By staying up to date with security updates and following best security practices, users can ensure their devices and communication sessions remain secure and resilient.

Timeline

Published on: 03/13/2023 12:15:00 UTC
Last modified on: 03/17/2023 13:19:00 UTC