CVE-2019-14284
Description
A vulnerability was found in the Linux kernel’s floppy disk driver implementation. A local attacker with access to the floppy disk device file (/dev/fd0 through to /dev/fdN) can create a situation that causes the kernel to divide by zero. This requires two consecutive ioctl calls to be issued. The first ioctl call sets the sector and rate values, and the second ioctl is the call to format the floppy disk to the appropriate values. This flaw can cause the system to divide by zero and panic the host. No media (floppy) is required to be inserted for this attack to work properly.
Mitigation
The kernel module named 'floppy' contains the affected code, this can be blacklisted using the standard blacklisting techniques or disabled in the systems BIOS. See https://access.redhat.com/solutions/41278 for how to blacklist a kernel module.
Virtualized guest systems can also remove the system from the guests configuration to ensure that the module does not load.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5 | 6.2 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | None | N/A |
| User Interaction | Required | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
NVD: CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
If an attacker can trigger the allocation of the limited resources, but the number or size of the resources is not controlled, then the most common result is denial of service. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment, i.e., the product may slow down, crash due to unhandled errors, or lock out legitimate users. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system.
Access Control,Other
Technical Impact: Bypass Protection Mechanism; Other
In some cases it may be possible to force the product to "fail open" in the event of resource exhaustion. The state of the product -- and possibly the security functionality - may then be compromised.
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