CVE-2022-1491 - Deep Dive Into Chrome’s Bookmark Use-After-Free Vulnerability

In the fast-moving world of browser vulnerabilities, some bugs stand out—not just for their technical depth but for their real-world impact on user safety. One such flaw is CVE-2022-1491, a "use-after-free" bug in Google Chrome’s Bookmarks component. Discovered by researcher Leecraso, this issue highlights the complex interactions between user interface features and browser memory management. In this article, we'll break down the bug, see how it can be exploited, and explain what it means for users and developers.

What is CVE-2022-1491?

In simple terms, CVE-2022-1491 is a vulnerability in how Chrome manages memory for bookmarks. Before Chrome version 101..4951.41, a flaw in the bookmark handling code could be abused to potentially corrupt the browser's memory (heap corruption). To take advantage of this bug, an attacker needed to use direct user interaction—for instance, tricking a user into clicking on something crafted on the attacker's web page.

Use-after-free bugs happen when a program continues to use a chunk of memory after it's been released. This can let attackers run their own code or even crash the program. In browsers, these vulnerabilities are especially dangerous because they are often the first step in more complex attacks.

Technical Details: How Does the Bug Work?

The vulnerability lives in the way Chrome manipulates Bookmark data. When you add, delete, or move bookmarks, a chain of internal "events" takes place. Chrome is designed to destroy certain memory objects when they’re no longer needed, but in this bug, due to improper handling, a pointer may still reference memory that’s already freed.

Here’s a simplified breakdown of the scenario:

If further actions reference the already-freed object, Chrome may access invalid memory.

Let’s look at a toy example using pseudo-code:

// Hypothetical example
class BookmarkManager {
    Bookmark* currentBookmark;
    void removeBookmark(Bookmark* bk) {
        delete bk;
        // <--- 'bk' is now freed
    }
    void processBookmarkEvent(Event* evt) {
        removeBookmark(evt->bookmark);
        // ..oops, code below still uses evt->bookmark
        renderBookmark(evt->bookmark); // Use-after-free occurs here!
    }
}

In the real Chrome code, the pattern is much more complex, but the principle is the same—accessing released memory.

Exploitation: What Could an Attacker Do?

By itself, the bug doesn’t let an attacker run arbitrary code. However, with some clever manipulation, it can corrupt Chrome’s memory heap. In the right hands, that often opens the door to:

Use the corrupted memory pointer to redirect the browser’s operation.

Note: Chrome’s internal sandbox and multi-process design makes RCE much harder, but not impossible.

Example Exploit Skeleton

While there is no known public "full exploit" for CVE-2022-1491, a 'proof of concept' often looks like this:

<!-- Sketch of malicious bookmark manipulation -->
<script>
function triggerBug() {
    let boom = document.createElement('a');
    boom.href = "javascript:bookmarkAction()";
    document.body.appendChild(boom);

    // Simulate user interaction: click the bookmarklet
    boom.click();

    function bookmarkAction() {
        // Rapidly remove and access bookmarks
        // E.g., remove bookmark and try to access it
        chrome.bookmarks.remove(/* ... */);
        chrome.bookmarks.get(/* ... */); // UAF potentially triggered
    }
}
</script>

*Please note: This is a theoretical example. Browsers may prevent direct abuse like this without explicit user actions.*

Who is at Risk?

All users running Google Chrome versions before 101..4951.41 could potentially be affected. Chromium-based browsers that didn’t patch promptly may also be vulnerable.

Action:

Patched: Included in Chrome 101..4951.41 (April 2022)

- CVE Record: CVE-2022-1491
- Chromium Issue: crbug.com/1302418

Keeping your browser up to date is the most important thing you can do to stay safe.

CVE-2022-1491 is a reminder that even small features in software have big impacts, and that attackers never stop looking for a way in.

Timeline

Published on: 07/26/2022 22:15:00 UTC
Last modified on: 08/15/2022 11:16:00 UTC