Security Bulletin: IBM i is vulnerable to bypass security restrictions due to Samba SMB1 (CVE-2021-43566 and CVE-2021-44141)

Security Bulletin

Summary

Samba is available on IBM i to provide file system access. Samba is vulnerable to the issues described in the vulnerability details section. IBM i has addressed the applicable CVEs in the Samba implementation by providing a fix.

Vulnerability Details

CVEID: CVE-2021-43566
DESCRIPTION: Samba could allow a remote authenticated attacker to bypass security restrictions, caused by a symlink race error. By using a specially-crafted SMB1 or NFS symlink, an attacker could exploit this vulnerability to create a directory in a part of the server file system not exported under the share definition.
CVSS Base score: 2.6
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/217058 for the current score.
CVSS Vector: (CVSS:3.0/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N)

CVEID: CVE-2021-44141
DESCRIPTION: Samba could allow a remote authenticated attacker to obtain sensitive information. By querying a symlink inside the exported share using SMB1 with unix extensions turned on, an attacker could exploit this vulnerability to discover if a named or directory exists on the filesystem outside of the exported share.
CVSS Base score: 6.5
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/218468 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N)

Affected Products and Versions

Affected Product(s)	Version(s)
IBM i	7.4
IBM i	7.3

Remediation/Fixes

The issues can be fixed by applying a PTF to IBM i. Releases 7.4 and 7.3 of IBM i will be fixed.

The IBM i PTF numbers containing the fix for the CVEs are:

Release 7.4 - SI78680
Release 7.3 - SI78679

https://www.ibm.com/support/fixcentral

Important note: IBM recommends that all users running unsupported versions of affected products upgrade to supported and fixed version of affected products.

Workarounds and Mitigations

None

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References

Complete CVSS v3 Guide
On-line Calculator v3

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Change History

28 Feb 2022: Initial Publication

*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.

Disclaimer

Review the IBM security bulletin disclaimer and definitions regarding your responsibilities for assessing potential impact of security vulnerabilities to your environment.

Document Location

Worldwide

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Tips

Security Bulletin: IBM i is vulnerable to bypass security restrictions due to Samba SMB1 (CVE-2021-43566 and CVE-2021-44141)