CVE-2018-9390: Out-of-Bounds Read in procfile_write of gl_proc.c Leads to Local Escalation of Privilege

The CVE-2018-9390 vulnerability has been identified in the procfile_write function within the gl_proc.c file. This security flaw allows for a possible out-of-bounds read of a function pointer, due to an incorrect bounds check. Exploiting this vulnerability could lead to a local escalation of privilege, where the attacker gains unauthorized access to sensitive information or system resources. To execute this attack, the attacker must already have system execution privileges, but user interaction is not required for exploitation.

The vulnerable code section can be found in gl_proc.c as shown below

int procfile_write(struct file *file, const char __user *buffer,
unsigned long count, void *data) {
ssize_t len;
int *fnidx;

len = min(count, (unsigned long)mgl_proc_len);
if (pointer_proc || !mgl_proc_whole)
return ;

if (copy_from_user(mgl_proc_buffer+ *///REDACTED/*/, buffer, len))
return -EFAULT;

len = strstrip(mgl_proc_buffer);

fnidx = bsearch(mgl_proc_buffer, /*/REDACTED/, len);
if (!fnidx)
return -EFAULT;

In this code, the bounds check is improperly handled, and this could potentially lead to an out-of-bounds read due to the usage of the bsearch function.

Exploit Details

According to the vulnerability details, the attacker needs system execution privileges to perform this attack. Once the attacker achieves this access level, they can exploit this security flaw by targeting the incorrect bounds check of the function pointer.

A successful attack will allow unauthorized users to perform actions only permitted to higher-privilege users, such as accessing sensitive information or manipulating system settings.

Original References

The CVE-2018-9390 identifier has been assigned to this vulnerability, and more information can be found at the following sources:

1. NVD - National Vulnerability Database: https://nvd.nist.gov/vuln/detail/CVE-2018-9390

2. Android Security Bulletin - August 2018: https://source.android.com/security/bulletin/2018-08-01

3. Android Open Source Project (AOSP) source code reference: https://android.googlesource.com/kernel/common/+/41afd58dddba7e/gldriver/gl_proc.c

Mitigation Strategies

To address this vulnerability, it is essential to apply security patches and maintain an up-to-date system. Google's Android Security Bulletin for August 2018 lists this vulnerability and includes details on patch availability. Additionally, it is crucial to minimize the number of users with system execution privileges on your device to reduce the attack surface. Limiting user access to sensitive information and managing user permissions carefully helps protect against potential exploitation of this vulnerability.

Conclusion

The CVE-2018-9390 vulnerability is a serious security flaw that could lead to local escalation of privilege. This issue stems from an incorrect bounds check in the procfile_write function of gl_proc.c, allowing attackers the potential to execute malicious actions on the affected system. Applying security patches and maintaining appropriate system access controls are crucial steps in protecting against this type of cybersecurity threat.

Timeline

Published on: 12/05/2024 23:15:04 UTC
Last modified on: 12/19/2024 16:49:41 UTC