A new critical vulnerability has been uncovered: CVE-2024-49730, found in the FuseDaemon.cpp file of a popular system component. This bug is a classic case of out-of-bounds write due to unchecked memory access, resulting in the possibility of memory corruption. The impact? A local user on the system can exploit this flaw to escalate their privileges — no user interaction or extra permissions required.

In this post, we’ll break down how the vulnerability works, show you simplified code snippets that highlight the problem area, examine a real exploit scenario, and share useful references for your research and mitigation.

What is CVE-2024-49730?

At its core, this vulnerability is caused by improper handling of buffer boundaries in the FuseDaemon.cpp file. The software fails to check if the memory it writes to actually belongs to the object in question, letting an attacker overwrite sensitive data. In the best case, this would just crash the process. In the worst case, a malicious local user could execute code with elevated privileges.

Here’s a simplified example resembling the faulty code found in FuseDaemon.cpp

// FuseDaemon.cpp

// The vulnerable function 
void FuseDaemon::handleRequest(const char* data, size_t data_size) {
    char buffer[128];

    // Vulnerability: No check if data_size > 128!
    memcpy(buffer, data, data_size);

    // Further processing...
}

What’s wrong?

- The code copies up to data_size bytes from an attacker-controlled buffer (data) into a 128-byte stack buffer (buffer) using memcpy.
- If data_size is greater than 128, the memcpy will write past the end of buffer, corrupting the stack.
- An attacker with local access can craft input to handleRequest() to control what gets written and where.

Exploiting the Bug

With this vulnerability, attackers don’t need special privileges or active help from the user — just local code execution (as a basic user) on the system.

Exploit Steps

1. Write Exploit Program: The attacker writes a program that interacts with the FuseDaemon process, sending it a bad request with a too-large payload.
2. Trigger Stack Corruption: The oversized buffer causes a stack smash, possibly overwriting return addresses or function pointers.
3. Execute Malicious Code: By skillfully planning the payload, the attacker gets the system to execute their own code with elevated privileges (e.g., root).

Here’s a proof-of-concept exploit in C that demonstrates the bug (conceptual)

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

// Normally this would talk to FuseDaemon using IPC or a file descriptor.
void sendPayload() {
    // Create an evil buffer (256 bytes, size > 128)
    char evil_data[256];
    memset(evil_data, 'A', sizeof(evil_data));
    // Normally, attacker would craft payload to control RIP/EIP here.
    
    // This would be sent to the vulnerable handleRequest function.
    // For PoC, you’d have to interface with the real service (pipe, socket, etc.)
    
    // Example: write to a pipe, shared memory, or custom IPC to FuseDaemon
}

int main() {
    sendPayload();
    printf("Payload sent. If daemon is vulnerable, system may be compromised.\n");
    return ;
}

*Note: Actual exploitation would need elevated skills, knowledge of FuseDaemon’s IPC mechanism, and often defeating stack guards/ASLR.*

No User Interaction Needed: Silent, automated exploits possible.

- Affects System Integrity: Any successful attack can let a local attacker take control of the entire system.

Is My System Affected?

Are you running a system or software that ships with FuseDaemon.cpp and you haven’t patched since early June 2024? There's a chance you’re at risk.

* Systems often affected: Certain Linux distros, Android-based OS, and embedded devices using FUSE-based daemons.
* Run strings $(which fusedaemon) | grep 49730 or check your vendor’s security advisories to confirm.

Patch

Vendors have released patches to fix this flaw by checking the buffer size before calling memcpy. Always keep your system and packages up to date.

Safe code example

void FuseDaemon::handleRequest(const char* data, size_t data_size) {
    char buffer[128];
    // Only copy up to buffer size!
    size_t safe_size = data_size > sizeof(buffer) ? sizeof(buffer) : data_size;
    memcpy(buffer, data, safe_size);
    // Handle error or log excessively large input
}

Restrict local user access: Only trusted users should have shell access until patched.

- Monitor suspicious activity: Use tools like auditd or SELinux/AppArmor to detect unusual FuseDaemon access.

Original References

- National Vulnerability Database: CVE-2024-49730
- GitHub Security Advisory for FuseDaemon
- Linux Kernel Mailing List: Security Patch Discussion (example)
- FUSE Project Homepage
- Common Weakness Enumeration: CWE-787 (Out-of-bounds Write)

Conclusion

CVE-2024-49730 is a vivid reminder that unchecked memory copying still leads to critical security holes today. If you’re running any system with FUSE or similar components, patch now and check your exposure! Local privilege escalation vulnerabilities like this are a favorite entry-point for attackers. Don’t be caught off guard.

Stay secure and keep your systems up to date!

*Exclusive author analysis — made simple for everyone. Please refer to the original references for the latest vendor details and patches.*

Timeline

Published on: 09/02/2025 23:15:32 UTC
Last modified on: 09/04/2025 16:40:08 UTC