It was discovered that the ghostscript /invalidaccess checks fail under certain conditions. An attacker could possibly exploit this to bypass the -dSAFER protection and, for example, execute arbitrary shell commands via a specially crafted PostScript document.
Find out more about CVE-2018-16509 from the MITRE CVE dictionary dictionary and NIST NVD.
This issue did affect the versions of ghostscript as shipped with Red Hat Enterprise Linux 5, 6, and 7.
Red Hat Enterprise Linux 5 is now in Extended Life Phase of the support and maintenance life cycle. This issue 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/.
| CVSS3 Base Score | 7.3 |
|---|---|
| CVSS3 Base Metrics | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L |
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | None |
| Scope | Unchanged |
| Confidentiality | Low |
| Integrity Impact | Low |
| Availability Impact | Low |
| Platform | Errata | Release Date |
|---|---|---|
| Red Hat Enterprise Linux 7 (ghostscript) | RHSA-2018:2918 | 2018-10-16 |
| Red Hat Enterprise Linux 6 (ghostscript) | RHSA-2018:3760 | 2018-12-03 |
| Platform | Package | State |
|---|---|---|
| Red Hat OpenShift Enterprise 3.2 | mediawiki | Not affected |
| Red Hat OpenShift Enterprise 3.1 | mediawiki | Not affected |
| Red Hat OpenShift Enterprise 3.0 | mediawiki | Not affected |
| Red Hat OpenShift Container Platform 3.9 | mediawiki | Not affected |
| Red Hat OpenShift Container Platform 3.7 | mediawiki | Not affected |
| Red Hat OpenShift Container Platform 3.6 | mediawiki | Not affected |
| Red Hat OpenShift Container Platform 3.5 | mediawiki | Not affected |
| Red Hat OpenShift Container Platform 3.4 | mediawiki | Not affected |
| Red Hat OpenShift Container Platform 3.3 | mediawiki | Not affected |
| Red Hat OpenShift Container Platform 3.11 | mediawiki | Not affected |
| Red Hat OpenShift Container Platform 3.10 | mediawiki | Not affected |
| Red Hat Enterprise Linux 5 | ghostscript | Will not fix |
ImageMagick relies on ghostscript when processing certain files formats. Thus, ImageMagick can be used as an attack vector. In order to prevent ImageMagick from processing those files on Red Hat Enterprise Linux 6 and 7, you can disable the use of ghostscript and the processing of PS, EPS, PDF, and XPS file formats in ImageMagick's security policy by opening /etc/ImageMagick/policy.xml and adding the following lines to the "<policymap>" section of the file:
<policy domain="coder" rights="none" pattern="PS" />
<policy domain="coder" rights="none" pattern="EPS" />
<policy domain="coder" rights="none" pattern="PDF" />
<policy domain="coder" rights="none" pattern="XPS" />
<policy domain="delegate" rights="none" pattern="gs" />
Additionally, this issue can be triggered when processing files in order to generate thumbnails, for example when browsing a folder containing a malicious PostScript file in Nautilus. To prevent this, remove or rename the "/usr/bin/evince-thumbnailer" executable.
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