CVE-2017-12762
Description
A buffer overflow was found in the Linux kernel's isdn_net_newslave() function in the /drivers/isdn/i4l/isdn_net.c file. An overflow happens when the user-controlled buffer is copied into a local buffer of constant size using strcpy() without a length check.
Statement
This issue affects the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 5, 6, 7 and Red Hat Enterprise MRG 2. This has been rated as having Low security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Mitigation
The ISDN kernel module is automatically loaded when the system boots and the ISDN service is present and enabled. The kernel modules can be prevented from being loaded by using system-wide modprobe rules. Run the following commands to blacklist the ISDN module, thus preventing them from loading:
# echo "install isdn /bin/true">> /etc/modprobe.d/disable-isdn.conf
On RHEL 6 execute the following commands as root to check if any isdn-related services are present:
# chkconfig --list | grep isdn
and disable them if they are:
# chkconfig isdn off
(or use a name of another isdn-related service)
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 | 4.7 | 9.8 | N/A |
| Attack Vector | Local | Network | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | High | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | High | N/A |
| Integrity Impact | Low | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of the product's implicit security policy. This can often be used to subvert any other security service.
Availability
Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU)
Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the product into an infinite loop.
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