CVE-2022-36227 is a security vulnerability discovered in libarchive, a widely used library for reading and writing archive files. Before version 3.6.2, the software does not check for an error after calling the calloc function, which may lead to a NULL pointer dereference. While some third parties dispute its potential for code execution, under rare circumstances, it might be possible for an attacker to leverage this vulnerability to execute arbitrary code.
Background
libarchive is a software library that provides a flexible interface for reading and writing various archive formats, such as tar, cpio, and ISO images, as well as reading and writing compressed data. It is widely used in tools like BSD's tar and the rpm packaging system, among others. This vulnerability affects libarchive versions before 3.6.2, which means that many applications relying on libarchive could be affected.
Vulnerability Details
The vulnerability lies in the improper error checking after calling the calloc function. calloc returns a NULL pointer when it fails, but in the vulnerable versions of libarchive, the software does not check for this failure. As a result, a NULL pointer dereference could occur.
Here's a code snippet illustrating the improper calloc usage
struct archive_entry *entry;
int* metadata;
entry = archive_entry_new();
metadata = calloc(1, sizeof(int));
// Missing check for metadata allocation failure.
archive_entry_set_metadata(entry, metadata);
If the calloc function call fails and returns NULL, the subsequent call to archive_entry_set_metadata will trigger a NULL pointer dereference when trying to access 'metadata'.
Exploit Scenario
While the vulnerability itself does not directly facilitate code execution, under rare circumstances, it might be possible for an attacker to exploit it to execute arbitrary code. Specifically, if NULL is equivalent to the x memory address and the privileged code can access it, an attacker could potentially read or write memory, leading to code execution.
However, scenarios that allow for this exploitation are uncommon, and it's essential to emphasize that most systems will not be vulnerable to code execution because of this bug.
Mitigation
To protect your system against potential exploitation of CVE-2022-36227, you should update libarchive to version 3.6.2 or later, which contains a fix for the vulnerability. The latest version is available from the official libarchive website at https://www.libarchive.org/.
After updating libarchive, you should also ensure that any tools or applications using the library are restarted to use the fixed version.
Conclusion
CVE-2022-36227 is a NULL pointer dereference vulnerability in libarchive before version 3.6.2. While it is rare for this vulnerability to lead to code execution, it is still vital to update the library to ensure proper error handling and prevent potential exploitation under exceptional circumstances. By using version 3.6.2 or later, systems running libarchive can prevent the NULL pointer dereference from occurring and protect themselves from any possible consequences of this bug.
Timeline
Published on: 11/22/2022 02:15:00 UTC
Last modified on: 02/06/2023 14:31:00 UTC