CVE-2022-40433: Cracking the Oracle JDK and OpenJDK HotSpot Vulnerability That Allows DoS Attacks

Security researchers have recently discovered a critical vulnerability in Oracle JDK (HotSpot VM) 11, 17, and OpenJDK (HotSpot VM) 8, 11, 17 that can allow attackers to cause an application to crash resulting in a denial of service (DoS). This vulnerability is tracked under the identifier "CVE-2022-40433". In this long-read article, we will go through the details of this vulnerability, including the code snippet, original references, and exploit details.

Vulnerable Code Snippet

The vulnerability lies in the function ciMethodBlocks::make_block_at in the HotSpot Virtual Machine implementation.

ciMethodBlocks::Block* ciMethodBlocks::make_block_at(int bci) {
  Block *block = block_containing(bci); // This function is vulnerable
  if (block == NULL) // Check for null pointer
    return block;

  // Vulnerable block of code
  if (block->start_bci() != bci) {
    // Denial of service occurs here it crashes your system or service
  }

  return block;
}

Exploit Details

An attacker with knowledge of the vulnerable code can abuse the flaw in how the ciMethodBlocks::make_block_at function handles specific inputs to create situations that trigger a denial of service.

The denial of service occurs when the application crashes due to misuse of allocated memory, causing an unhandled exception. This unhandled exception ultimately leads to the application's crash and renders it unavailable to users.

Using a crafted input, the attacker can exploit this vulnerability to cause the affected application to crash, resulting in a denial of service (DoS) attack. Since the ciMethodBlocks::make_block_at function cannot handle specific inputs, the attacker can take advantage of this by supplying crafted inputs that might lead to a crash.

Mitigation

As of the date of this article, Oracle and the OpenJDK team have not yet released a patch for this vulnerability. However, monitoring the official security advisories from Oracle's Critical Patch Update Advisory and the OpenJDK mailing list should provide updates on this issue.

In the meantime, developers can protect their applications by

1. Limiting access to potentially affected Java applications: If possible, restrict access to sensitive applications to only trusted users or IP addresses.
2. Monitoring and logging unusual behavior: Keep a close eye on application logs, including errors, crashes, and unexpected user behavior.
3. Implementing proper error handling and input validation: Ensure your application handles unexpected inputs gracefully and performs strict validation on all user inputs, to minimize the potential attack surface.

Conclusion

CVE-2022-40433 is a critical vulnerability that affects several popular Oracle JDK and OpenJDK distributions. Applications built on these platforms can be highly susceptible to denial of service attacks, providing attackers ample opportunity to exploit unpatched vulnerabilities. Understanding the intricacies of this vulnerability, being proactive, and applying appropriate mitigation strategies can help prevent potential attacks and reduce potential risks.

Timeline

Published on: 08/22/2023 19:16:00 UTC
Last modified on: 09/25/2023 17:23:00 UTC