CVE-2023-36281: Uncovering a Critical Vulnerability in langchain v...171

In this post, we will be delving into the details of a recently discovered security vulnerability, CVE-2023-36281, which affects langchain version ..171. This critical vulnerability allows a remote attacker to execute arbitrary code on the affected system through a specially crafted JSON file. We'll be taking a closer look at the root cause of this issue, explaining how it can be exploited, and providing some guidance on mitigating the risk.

Background

Langchain is a popular language processing library that has been widely used in numerous applications. However, a critical security vulnerability has been identified in version ..171, which could have serious implications for the affected systems. Specifically, this vulnerability is related to the load_prompt function, which is used for processing user input in the form of JSON files.

Vulnerability Details

The core issue lies within the improper handling of input, specifically with the use of the __subclasses__ attribute and the template processing functionality of langchain. An attacker could create a malicious JSON file containing arbitrary code, and by exploiting this vulnerability, they could gain remote code execution on the targeted system.

Here's a simple code snippet illustrating the vulnerable function, load_prompt

def load_prompt(prompt_file):
    with open(prompt_file, 'r') as f:
        prompt_data = json.load(f)
    prompt_class = next(cls for cls in Prompt.__subclasses__() if cls.__name__ == prompt_data['class'])
    return prompt_class.from_json(prompt_data)

Exploitation

To exploit this vulnerability, an attacker could craft a malicious JSON file tailored to take advantage of the improper handling of __subclasses__ and template processing. By manipulating the input data in the JSON file and bypassing the intended checks, the attacker can execute arbitrary code on the targeted system. Here's a sample of a malicious JSON file:

{
  "class": "TemplateInjectionClass",
  "data": {
    "template": "{{ arbitrary_code_to_be_executed }}"
  }
}

The attacker crafts a malicious JSON file as shown above.

2. The victim, using the affected langchain v...171, processes the attacker's JSON file using the load_prompt function
3. The arbitrary code within the JSON file is executed on the victim's system, potentially leading to unauthorized access or other detrimental effects.

Mitigation and Prevention

To minimize the impact of this vulnerability, it is strongly recommended that users of langchain v...171 upgrade to the latest version of the library, which contains a fix for this issue. If an upgrade is not feasible in the immediate future, users should apply proper input validation mechanisms to sanitize and verify the JSON files before they are processed by load_prompt.

Additional measures such as restricting access to the application and implementing network-level filters can also help to limit the potential for exploitation.

Conclusion

CVE-2023-36281 is a critical vulnerability that affects language processing library langchain v...171. By taking advantage of this vulnerability, an attacker can remotely execute arbitrary code on the targeted system. Immediate action should be taken to patch the affected systems, and additional security measures should be implemented to prevent future exploitation.

Original references

- CVE-2023-36281 - National Vulnerability Database
- langchain v...171 Security Advisory

Stay safe and ensure that your systems are up to date to protect against such vulnerabilities!

Timeline

Published on: 08/22/2023 19:16:36 UTC
Last modified on: 11/17/2023 19:15:08 UTC