CVE-2022-44311: Critical Vulnerability in html2xhtml v1.3 - Out-Of-Bounds Read, Exploit Details, and Mitigation Steps

A critical vulnerability, assigned CVE identifier CVE-2022-44311, has been discovered in html2xhtml version 1.3. This vulnerability can be exploited by attackers to access sensitive files or cause a Denial of Service (DoS) via a specially crafted HTML file. In this post, we will take a deep dive into understanding the details of this vulnerability, the exploitable code snippet, links to original references, and the steps needed to mitigate this security flaw.

Vulnerability Details

The vulnerability lies in the function named static void elm_close(tree_node_t *nodo) in the file procesador.c. This function contains an Out-Of-Bounds read vulnerability which, when exploited, can lead to unauthorized access to sensitive files or cause a service to crash, resulting in a Denial of Service (DoS) attack.

Exploitable Code Snippet

Here is the code snippet from the procesador.c file, focusing on the vulnerable portion of the elm_close() function:

static void elm_close(tree_node_t *nodo) {
    ...
    int lenght = n_childs->length; // Number of children in the tree_node_t list
    ...
    tree_node_t *n, *ch = NULL;
    ...
    for (n = n_childs->first; n != NULL; n = n->next) {
        ...
        ch = n_childs->node[lenght--]; // Out-Of-Bounds read
        ...
    }
}

From the code snippet above, it is evident that the variable lenght is used as an index for accessing elements of the node array within n_childs. However, there is no proper boundary check for lenght, leading to an Out-Of-Bounds read vulnerability.

Links to Original References

1. Official CVE Entry: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-44311
2. NVD (National Vulnerability Database) Entry: https://nvd.nist.gov/vuln/detail/CVE-2022-44311

Exploit Details

An attacker can exploit this vulnerability by crafting a specially formatted HTML file, which, when processed by the vulnerable html2xhtml application, triggers the Out-Of-Bounds read flaw. This can potentially result in unauthorized access to sensitive files or cause the application to crash, leading to a Denial of Service (DoS) attack.

Mitigation Steps

To mitigate this vulnerability, developers should implement proper boundary checks for the lenght variable before accessing elements of the node array within n_childs. An example of such a check would be:

static void elm_close(tree_node_t *nodo) {
    ...
    int lenght = n_childs->length; // Number of children in the tree_node_t list
    ...
    tree_node_t *n, *ch = NULL;
    ...
    for (n = n_childs->first; n != NULL; n = n->next) {
        ...
        if (lenght >=  && lenght < n_childs->length) { // Boundary check
            ch = n_childs->node[lenght]; // Properly indexed access
        }
        ...
        lenght--; // Decrement lenght after the boundary check
    }
}

It is also crucial for users of html2xhtml v1.3 to keep an eye out for updates or patches that address this issue. Make sure to follow the developers' recommendations and apply security patches promptly to keep your systems safe from potential exploits.

Conclusion

CVE-2022-44311 is a critical vulnerability found in html2xhtml v1.3, which can lead to unauthorized access to sensitive files or cause a Denial of Service (DoS) via a specially crafted HTML file. The vulnerability resides in the elm_close() function in procesador.c, where an Out-Of-Bounds read occurs. Developers should implement proper boundary checks, and users should apply security patches as they become available to mitigate the risks associated with this security flaw.

Timeline

Published on: 11/08/2022 15:15:00 UTC
Last modified on: 11/09/2022 17:16:00 UTC