In recent times, a newly discovered vulnerability, CVE-2022-48468, has caught the attention of developers and security researchers. This post will provide an in-depth analysis of this vulnerability, affecting protobuf-c before version 1.4.1, with a focus on understanding the unsigned integer overflow in the parse_required_member function. We shall also discuss the potential exploit details and suggest mitigation steps. Let's dive into the details!

Vulnerability Details

Protobuf-c, a popular C implementation of the Google Protocol Buffers, uses a language-neutral and platform-neutral method for serializing structured data. The vulnerability lies in the parse_required_member function, which contains an unsigned integer overflow, leading to potential security risks.

The affected function is present in the protobuf-c/protobuf-c.c source code file. The exact code snippet responsible for the vulnerability is as follows:

static protobuf_c_boolean
parse_required_member(ParseContext *context,
          unsigned value_ofs,
          RequiredFieldGenerator *out)
{
  const char *ptr = context->scanner.next;
  ...
  size_t len = parse_ctype(context, &out->ctype);
  ...
  if (len >= UINT_MAX)
    return FALSE;
  ...
}

In the above code snippet, the 'len' value is parsed from the input data, and when its value is equal to or greater than UINT_MAX (the maximum value of an unsigned integer), the function returns FALSE.

Original References

1. The protobuf-c GitHub repository: https://github.com/protobuf-c/protobuf-c
2. The commit history, containing the changes to mitigate this vulnerability: https://github.com/protobuf-c/protobuf-c/commit/4f4cee2d7ff9748236e2c229232ae9d9b84a88fd

Exploit Details

An attacker can potentially exploit this vulnerability by crafting a specially designed .proto file or malformed binary data that triggers an unsigned integer overflow. This could result in incorrect parsing of data and could ultimately lead to memory corruption or malicious code execution.

Since protobuf-c is widely used in many applications and services, the risk associated with this vulnerability depends on the affected software's security implications. If left unpatched, this security flaw puts systems at an increased risk of being exploited, potentially compromising sensitive information.

Mitigation

The protobuf-c developers have addressed this vulnerability in version 1.4.1 of the library. To protect your systems and applications, consider applying the following mitigation steps:

Limit the size of .proto files and binary data passed to protobuf-c parsers if possible.

4. Use a robust input validation mechanism that helps prevent potential malformed data from reaching your system.

Conclusion

CVE-2022-48468 sheds light on a notable unsigned integer overflow vulnerability affecting protobuf-c before version 1.4.1. Although the exploit details vary depending on affected systems, one cannot undermine the potential risks involved. By updating to the latest version of protobuf-c and implementing appropriate mitigation measures, developers can better ensure the security and integrity of their applications and services.

Timeline

Published on: 04/13/2023 21:15:00 UTC
Last modified on: 04/21/2023 18:25:00 UTC