Recently, a significant vulnerability, CVE-2022-41409, was identified in the pcre2test utility. This utility is a part of the PCRE2 (Perl Compatible Regular Expressions 2) library, which is widely used for implementing regular expression pattern matching using the same syntax and semantics as Perl 5. The PCRE2 library is used in various programming languages and applications.
This vulnerability, existing in pcre2test versions prior to 10.41, is an integer overflow vulnerability that can allow an attacker to cause a denial of service or potentially other undefined impacts by providing negative input values to the target application.
This blog post aims to provide an in-depth overview of this vulnerability, some sample code to demonstrate it, links to the original references, and insight into potential exploitation techniques.
An integer overflow occurs when a program attempts to store a value that is larger than the maximum value that can be represented by the available bits allocated for that variable. When this happens, the value "wraps around" to the minimum value for that data type, causing unexpected results.
In the case of CVE-2022-41409, the vulnerability stems from the improper handling of negative input values, resulting in an integer overflow. By providing a specifically crafted negative value, an attacker can trigger the overflow, potentially causing a Denial of Service (DoS) situation or even potentially exploiting it for other unspecified impacts in the target application.
1. Official CVE record: CVE-2022-41409 on MITRE.org
2. NVD information: National Vulnerability Database (NVD) Entry
3. PCRE2 project repository: PCRE2 Official GitHub Repository
The below code snippet is taken from the pcre2test utility, demonstrating the vulnerable code in versions before 10.41:
// ... intptr_t length = (intptr_t)data[length_position] << 8 | (intptr_t)data[length_position + 1]; length += -MIN_PRIVATESPACE; // ...
By providing a negative value for 'data[length_position]' and 'data[length_position + 1]', we can trigger an integer overflow. This can lead to an unanticipated result, making the program behave unexpectedly and potentially causing a denial of service or other undesired consequences.
To exploit this vulnerability (particularly for a denial of service attack), an attacker must craft a payload that invokes integer overflow by providing negative input values. This payload can be sent to the target application running the vulnerable version of pcre2test, causing the program to crash or behave unexpectedly.
Due to the nature of integer overflow vulnerabilities, it may also be possible to exploit this issue in a more severe manner to execute arbitrary code on a vulnerable system. However, such exploitation often requires clever manipulation of the application's memory layout and execution flow, which is beyond the scope of this blog post.
The integer overflow vulnerability present in pcre2test before version 10.41 is a crucial security concern for any application using the older versions of the PCRE2 library. By understanding the nature of the vulnerability, its potential exploitation, and the importance of using the latest fixed version, developers and administrators can keep their systems secure and prevent the potentially disastrous results of a successful attack.
To mitigate this vulnerability, it is strongly recommended that users and developers update pcre2test to version 10.41 or later. Links to the official PCRE2 repository and release notes can be found in the "Original References" section of this post.
Published on: 07/18/2023 14:15:00 UTC
Last modified on: 07/27/2023 03:46:00 UTC