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Security Bulletin: Vulnerability in the AIX smbcd daemon (CVE-2021-38993)

Security Bulletin


Summary

There is a vulnerability in the AIX smbcd daemon.

Vulnerability Details

CVEID:   CVE-2021-38993
DESCRIPTION:   IBM AIX could allow a non-privileged local user to exploit a vulnerability in the smbcd daemon to cause a denial of service.
CVSS Base score: 6.2
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/212962 for the current score.
CVSS Vector: (CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Affected Products and Versions

Affected Product(s)Version(s)
AIX7.1
AIX7.2
AIX7.3
VIOS3.1

 

The following fileset levels are vulnerable:

FilesetLower LevelUpper Level
smbc.rte7.1.0.07.1.302.6
smbc.rte7.2.0.07.2.302.6

 

To determine if your system is vulnerable, execute the following commands:
 
        lslpp -L | grep -i smbc.rte
 
 

Remediation/Fixes

A. FIXES
 
The fixes can be downloaded via ftp or http from:
 
 
The latest SMB client fileset may also be downloaded from:
 
To extract the fixes from the tar file:
 
For AIX 7.1:
tar xvf smbcd_fix.tar
gunzip smbc_302_fileset_71.tar.gz | tar xvf
 
For AIX 7.2, 7.3, and VIOS 3.1:
tar xvf smbcd_fix.tar
gunzip smbc_302_fileset_72.tar.gz | tar xvf
 
IMPORTANT: If possible, it is recommended that a mksysb backup of the system be created.  Verify it is both bootable and readable before proceeding.
 
To preview the fix installation:
 
installp -apYd . smbc
 
To install the fix package:
 
installp -aXYd . smbc
 
Verify you have retrieved the fixes intact:
 
The checksums below were generated using the "openssl dgst -sha256 [file]" command as the following:
 
openssl dgst -sha256 filename
82386d9913a386c234dcef6bafa53c803d173760218cea34b94645ab18a89f1fsmbc_302_fileset_71.tar.gz
ee3966422b87e95b3cdba9537f6276c8e48be9d89ca409fbd258c2a20230034bsmbc_302_fileset_72.tar.gz
 
These sums should match exactly. The OpenSSL signatures in the tar file and on this advisory can also be used to verify the integrity of the fixes.  If the sums or signatures cannot be confirmed, contact IBM AIX Support at https://ibm.com/support/ and describe the discrepancy.
            
openssl dgst -sha256 -verify [pubkey_file] -signature [advisory_file].sig [advisory_file]
 
openssl dgst -sha256 -verify [pubkey_file] -signature [fix_file].sig [fix_file]
 
Published advisory OpenSSL signature file location:
 

Workarounds and Mitigations

None

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References

Complete CVSS v3 Guide
On-line Calculator v3

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Related Information

IBM Secure Engineering Web Portal
IBM Product Security Incident Response Blog

AIX Security Bulletin (ASCII format)

Change History

24 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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Document Information

Modified date:
24 February 2022

UID

ibm16559320

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