Vulnerability CVE-2023-21918 has recently surfaced in the Oracle Database Recovery Manager component of Oracle Database Server. Supported versions affected include 19c and 21c. This post aims to deconstruct the exploit by outlining how the vulnerability has the potential to seriously impact additional products. An easily exploitable vulnerability permits high privileged attackers having Local SYSDBA privilege with network access via Oracle Net to compromise the Oracle Database Recovery Manager, resulting in unauthorized abilities such as causing a hang or frequently repeatable crash, known as a complete Denial of Service (DoS).

Original References

1. Oracle Security Advisory:
2. NIST National Vulnerability Database (NVD):
3. CVSS 3.1 Base Score Calculation:

Code Snippet

The following snippet is a simplified example of how an attacker might trigger the vulnerability in Oracle Database Recovery Manager:

import socket

def exploit(host: str, port: int):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.connect((host, port))
    payload = "Exploit_Payload_Goes_Here"
    sql_command = "ALTER SYSTEM SET events '11961 TRACE NAME ERRORSTACK LEVEL 3';"
    sock.send(payload + sql_command)
    data = sock.recv(1024)
    print("Received:", data)

if __name__ == "__main__":
    target_host = "Target_Oracle_Server_IP_Address"
    target_port = 1521  # Default Oracle Net Listener Port
    exploit(target_host, target_port)

Exploit Details

The vulnerability CVE-2023-21918 is a critical one, as it falls into the category of Availability impacts with a CVSS 3.1 Base Score of 6.8. The CVSS Vector breakdown is as follows: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H).

Availability (A): High (H)

The vulnerability essentially allows a high privileged attacker with Local SYSDBA privileges and network access via Oracle Net to compromise the Oracle Database Recovery Manager. This can lead to unauthorized abilities such as a complete DOS (Denial of Service), causing a hang or frequently repeatable crashes in the Oracle Database Recovery Manager.

It is highly recommended for organizations using Oracle Database Server 19c and 21c to address this vulnerability as soon as possible, as even though the vulnerability lies in Oracle Database Recovery Manager, attacks may significantly impact additional products, causing scope changes.

Way Forward

To safeguard against this critical vulnerability, it is essential to apply the necessary Oracle patches provided in the Oracle Security Advisory. Regularly monitoring and updating systems with the latest security patches is crucial in maintaining a secure environment and minimizing the risk of vulnerabilities like CVE-2023-21918.


Published on: 04/18/2023 20:15:00 UTC
Last modified on: 04/18/2023 20:37:00 UTC