zsh up to 5.3 Symlink Expansion utils.c memory corruption

CVSS Meta Temp Score
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CTI Interest Score
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8.4$0-$5k0.00

Summaryinfo

A vulnerability classified as critical has been found in zsh up to 5.3. This impacts an unknown function of the file utils.c of the component Symlink Expansion. The manipulation leads to memory corruption. This vulnerability is listed as CVE-2017-18206. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in zsh up to 5.3. It has been rated as critical. This issue affects some unknown processing of the file utils.c of the component Symlink Expansion. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In utils.c in zsh before 5.4, symlink expansion had a buffer overflow.

The bug was discovered 05/09/2017. The weakness was presented 02/27/2018 with Red Hat (Website). It is possible to read the advisory at sourceforge.net. The identification of this vulnerability is CVE-2017-18206 since 02/27/2018. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability was handled as a non-public zero-day exploit for at least 294 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 109139 (Amazon Linux 2 : zsh (ALAS-2018-986)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Amazon Linux Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 157839 (Oracle Enterprise Linux Security Update for zsh (ELSA-2018-3073)).

Upgrading to version 5.4 eliminates this vulnerability. A possible mitigation has been published 2 months after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Tenable (109139) and SecurityFocus (BID 103359†). See VDB-113890, VDB-113891, VDB-113902 and VDB-113922 for similar entries. Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.5
VulDB Meta Temp Score: 8.4

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔍

CVSSv2info

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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Memory corruption
CWE: CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 109139
Nessus Name: Amazon Linux 2 : zsh (ALAS-2018-986)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 65476
OpenVAS Name: Fedora Update for zsh FEDORA-2018-9cdf18a850
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍

Upgrade: zsh 5.4
Patch: sourceforge.net

Timelineinfo

05/09/2017 🔍
02/27/2018 +294 days 🔍
02/27/2018 +0 days 🔍
02/27/2018 +0 days 🔍
02/28/2018 +1 days 🔍
03/09/2018 +9 days 🔍
04/05/2018 +27 days 🔍
04/18/2018 +13 days 🔍
02/16/2023 +1765 days 🔍

Sourcesinfo

Advisory: RHSA-2018:1932
Organization: Red Hat
Status: Confirmed

CVE: CVE-2017-18206 (🔍)
GCVE (CVE): GCVE-0-2017-18206
GCVE (VulDB): GCVE-100-113903
SecurityFocus: 103359 - Zsh 'exec.c:hashcmd()' Function Local Denial of Service Vulnerability

See also: 🔍

Entryinfo

Created: 02/28/2018 08:17
Updated: 02/16/2023 08:08
Changes: 02/28/2018 08:17 (76), 01/09/2020 09:29 (5), 02/16/2023 08:08 (5)
Complete: 🔍
Cache ID: 216::103

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