CVE-2015-7977
Description
A NULL pointer dereference flaw was found in the way ntpd processed 'ntpdc reslist' commands that queried restriction lists with a large amount of entries. A remote attacker could potentially use this flaw to crash ntpd.
Statement
This issue affects the versions of ntp as shipped with Red Hat Enterprise Linux 5, 6, and 7. Red Hat Product Security has rated this issue as having Moderate security impact. A future update may address this issue in Red Hat Enterprise Linux 6 and 7. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.
Mitigation
Keep the number of restriction list entries in ntp.conf lower than 500.
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).
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.3 | 4.3 | N/A |
| Attack Vector | Network | Network | N/A |
| Access Complexity | Medium | Medium | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | Partial | Partial | N/A |
Vector
Red Hat: AV:N/AC:M/Au:N/C:N/I:N/A:P
NVD: AV:N/AC:M/Au:N/C:N/I:N/A:P
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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