Brute-force attack in Samba



Published: 2023-01-24
Risk Low
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-20251
CWE-ID CWE-362
Exploitation vector Local network
Public exploit N/A
Vulnerable software
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Samba
Server applications / Directory software, identity management

Vendor Samba

Security Bulletin

This security bulletin contains one low risk vulnerability.

1) Race condition

EUVDB-ID: #VU71486

Risk: Low

CVSSv3.1:

CVE-ID: CVE-2021-20251

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a brute-force attack.

The vulnerability exists due to a race condition in Samba when incrementing bad password attempts. Each connection to Samba gets a separate process, and each process loads, increments, and saves the bad password count without any coordination. A remote attacker can perform a brute-force attack using multiple threats and bypass imposed limits on the number of allowed incorrect passwords.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Samba: 4.1.0 - 4.17.0, 4.16.0 - 4.16.7, 4.15.0 - 4.15.13, 4.14.0 - 4.14.14, 4.13.0 - 4.13.17, 4.12.0 - 4.12.15, 4.11.0 - 4.11.17, 4.10.0 - 4.10.18, 4.9.0 - 4.9.18, 4.8.0 - 4.8.12, 4.7.0 - 4.7.12, 4.6.0 - 4.6.16, 4.5.0 - 4.5.16, 4.4.0 - 4.4.16, 4.3.0 - 4.3.13, 4.2.0 - 4.2.14


CPE2.3 External links

http://bugzilla.samba.org/show_bug.cgi?id=14611
http://gitlab.com/samba-team/samba/-/merge_requests/2708

Q & A

Can this vulnerability be exploited remotely?

How the attacker can exploit this vulnerability?

Is there known malware, which exploits this vulnerability?



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