CVE-2018-19044
Description
From CVE.org
keepalived 2.0.8 didn't check for pathnames with symlinks when writing data to a temporary file upon a call to PrintData or PrintStats. This allowed local users to overwrite arbitrary files if fs.protected_symlinks is set to 0, as demonstrated by a symlink from /tmp/keepalived.data or /tmp/keepalived.stats to /etc/passwd.
Statement
This issue affects the versions of keepalived as shipped with Red Hat Enterprise Linux 6 and 7.
Red Hat Enterprise Linux 6 is now in Maintenance Support 2 Phase of the support and maintenance life cycle. This has been rated as having a security impact of Moderate, 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/.
The keepalived packages shipped with Red Hat Enterprise Linux 6 and 7 are not built with dbus support, therefore vulnerable PrintData and PrintStats methods are not compiled in resulting RPM, which means this issue cannot be exploited via dbus messages on Red Hat Enterprise Linux 6 and 7. However, creation of pidfiles is also vulnerable to symlink attack and it is possible for local attacker to overwrite arbitrary file with the process identifiers of keepalived processes, but only if keepalived was launched with option to change pidfile location pointing to unsafe location and attacker is able to exploit Time-of-check Time-of-use race condition and create a symlink during a very small time frame in the same location the pidfile was specified. The default location used for pidfiles is safe. Red Hat Enterprise Linux 7 is by default configured with fs.protected_symlinks=1 which largely mitigates symlink attacks.
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 v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7 | 4.7 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | None | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | None | N/A |
Vector
Red Hat: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Confidentiality,Integrity,Access Control
Technical Impact: Read Files or Directories; Modify Files or Directories; Bypass Protection Mechanism
An attacker may be able to traverse the file system to unintended locations and read or overwrite the contents of unexpected files. If the files are used for a security mechanism then an attacker may be able to bypass the mechanism.
Other
Technical Impact: Execute Unauthorized Code or Commands
Windows simple shortcuts, sometimes referred to as soft links, can be exploited remotely since a ".LNK" file can be uploaded like a normal file. This can enable remote execution.
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