New Zero Day: CVE-2023-21823, Zero-day vulnerability in Windows

Buffer overflow

Zero Day Released – 2023-02-14
Patch Released – 2023-02-14


The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a boundary error within the Windows Graphics Component. A local user can trigger memory corruption and execute arbitrary code with SYSTEM privileges.

Note, the vulnerability is being actively exploited in the wild.

CWE-ID: CWE-119 – Memory corruption / Buffer Overflow

CWE-119 is a common weakness in software security, classified as “Improper Restriction of Operations within the Bounds of a Memory Buffer” by the Common Weakness Enumeration (CWE) standard. This weakness can lead to buffer overflow vulnerabilities, which occur when a program attempts to write data to a memory buffer beyond its intended bounds. Buffer overflow vulnerabilities can be exploited by attackers to execute arbitrary code or cause a program to crash.

The CWE-119 weakness typically occurs when a program uses a fixed-size buffer to hold data that can vary in size, such as input received from a network or user input. If the amount of data received exceeds the size of the buffer, the program may write the excess data to adjacent memory locations, potentially overwriting data that is used to control the program’s behavior. This can lead to a variety of consequences, ranging from unexpected program behavior to remote code execution.

Buffer overflow vulnerabilities can be difficult to detect and exploit, as the specific behavior of the program will depend on the contents of the overwritten memory locations. However, attackers can use techniques such as heap spraying or return-oriented programming (ROP) to increase the likelihood of successful exploitation.

To prevent buffer overflow vulnerabilities, software developers can use a variety of techniques, including input validation, range checking, and the use of dynamically allocated memory. When using fixed-size buffers, developers can also use functions such as strncpy or snprintf that include a size parameter to ensure that the buffer is not overwritten. Finally, developers should use programming languages and libraries that provide memory safety guarantees, such as Java or Rust, whenever possible.

Overall, the CWE-119 weakness represents a significant security risk for many types of software applications. It is important for developers to follow best practices for secure software development, including regular code reviews and vulnerability scanning, to minimize the risk of buffer overflow vulnerabilities and other types of software weaknesses.

Advisory: Microsoft Advisory

Vulnerable component: Windows

CVSSv3 score: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

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