In April 2024, a critical vulnerability surfaced across several embedded platforms: CVE-2024-43047. This flaw allows attackers to corrupt system memory when high-level operating system (HLOS) memory maps are handled. Let’s break down what’s happening, explore the exploit, and see how you can protect yourself.

What Is CVE-2024-43047?

CVE-2024-43047 is a memory corruption issue found in the routines responsible for maintaining HLOS memory maps. It commonly impacts custom kernels or drivers found in embedded or mobile environments—especially those integrating third-party memory sharing or mapping code.

This vulnerability often arises because the code mishandles pointers or fails to properly check memory boundaries. Especially dangerous in devices with Direct Memory Access (DMA) or loosely validated user-kernel memory operations, this bug can be used by attackers for privilege escalation or even remote code execution in certain scenarios.

Example Scenario

A faulty user-space call triggers a memcpy or buffer operation with unvalidated size or offset. If an attacker can control these offsets or buffer contents, they can overwrite crucial kernel data structures.

Impact: Elevation of privilege, system crash (DoS), or arbitrary code execution.

- Affected: Hardware with custom HLOS memory managers (some Android phones, IoT devices, embedded Linux platforms).

References

- NIST CVE Detail Page
- Qualcomm Security Bulletin (June 2024)

The problematic code is often in custom kernel drivers, like this (simplified for clarity)

// Vulnerable code: no bounds check on 'length'
int map_memory(int user_fd, size_t length) {
    void *kaddr;

    // Bad: length is passed directly from user
    kaddr = kmalloc(length, GFP_KERNEL);
    if (!kaddr)
        return -ENOMEM;

    if (copy_from_user(kaddr, user_buffer, length))
        return -EFAULT;

    // ... further operations ...
    return ;
}

Fail, returning NULL. If no check exists after, later code might use a NULL pointer.

More subtle exploit: If the length isn’t properly checked, an attacker can cause overflows, sometimes reaching adjacent kernel data and structures.

1. Open vulnerable device

int fd = open("/dev/hmem_map", O_RDWR);

2. Send malicious map request

struct map_req {
    void *user_buf;
    size_t len;
};

// Craft structure with huge length
struct map_req req;
req.user_buf = <valid_userspace_addr>;
req.len = xFFFFFFFF; // Very large value

ioctl(fd, MAP_IOC_CREATE, &req); // Hypothetical ioctl

Resources

- Binary Exploitation on Embedded Linux
- Android Kernel Exploitation Techniques

Defensive Measures

1. Update
Apply all patches from your hardware vendor or firmware provider as soon as possible.

2. Harden Kernel Drivers

Use memory-safe primitives when possible.

3. Enable Mitigations
- Enable SMAP/SMEP and kernel address space randomization.

Use hardened custom build options for your kernel.

4. Monitoring
- Watch logs for unexpected /dev access patterns or repeated kernel faults.

Conclusion

CVE-2024-43047 is a classic example of a memory mapping bug posing big risks in embedded and mobile systems. Exploiting simple coding mistakes, attackers can achieve major system compromise.

Key takeaway: Always treat input from userland with suspicion—especially when mapping memory. Update your systems and audit custom kernel additions.

For more info

- Official CVE Entry
- Upstream Patch Discussion

Stay vigilant—memory bugs like these are bread and butter for attackers in 2024! 🛡️

Timeline

Published on: 10/07/2024 13:15:15 UTC
Last modified on: 10/09/2024 14:39:06 UTC