CVE-2021-27876 : An issue was discovered in Veritas Backup Exec before 21.2. The communication be

An issue was discovered in Veritas Backup Exec before 21.2. The communication between a client and an Agent requires successful authentication, which is typically completed over a secure TLS communication. However, due to a vulnerability in the SHA Authentication scheme, an attacker is able to gain unauthorized access and complete the authentication process. Subsequently, the client can execute data management protocol commands on the authenticated connection. By using crafted input parameters in one of these commands, an attacker can access an arbitrary file on the system using System privileges.

Published 2021-03-01 22:15:14

Updated 2022-09-27 20:14:17

Source MITRE

View at NVD, CVE.org

Vulnerability category: BypassGain privilege

Products affected by CVE-2021-27876

Veritas » Backup Exec
Versions before (<) 21.2
cpe:2.3:a:veritas:backup_exec:*:*:*:*:*:*:*:*
Matching versions

CVE-2021-27876 is in the CISA Known Exploited Vulnerabilities Catalog

This issue is known to have been leveraged as part of a ransomware campaign.

CISA vulnerability name:

Veritas Backup Exec Agent File Access Vulnerability

CISA required action:

Apply updates per vendor instructions.

CISA description:

Veritas Backup Exec (BE) Agent contains a file access vulnerability that could allow an attacker to specially craft input parameters on a data management protocol command to access files on the BE Agent machine.

Notes:

https://www.veritas.com/support/en_US/security/VTS21-001; https://nvd.nist.gov/vuln/detail/CVE-2021-27876

Added on 2023-04-07 Action due date 2023-04-28

Exploit prediction scoring system (EPSS) score for CVE-2021-27876

EPSS FAQ

74.31%

Probability of exploitation activity in the next 30 days EPSS Score History

~ 98 %

Percentile, the proportion of vulnerabilities that are scored at or less

Metasploit modules for CVE-2021-27876

Veritas Backup Exec Agent Remote Code Execution

Disclosure Date: 2021-03-01

First seen: 2022-12-23

exploit/multi/veritas/beagent_sha_auth_rce

Authors: - Alexander Korotin <0xc0rs@gmail.com>

More information

CVSS scores for CVE-2021-27876

Base Score	Base Severity	CVSS Vector	Exploitability Score	Impact Score	Score Source
7.5	HIGH	AV:N/AC:L/Au:S/C:C/I:P/A:N	8.0	7.8	NIST
Access Vector: Network Access Complexity: Low Authentication: Single Confidentiality Impact: Complete Integrity Impact: Partial Availability Impact: None
8.1	HIGH	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N	2.8	5.2	MITRE
Attack Vector: Network Attack Complexity: Low Privileges Required: Low User Interaction: None Scope: Unchanged Confidentiality: High Integrity: High Availability: None
8.1	HIGH	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N	2.8	5.2	NIST
Attack Vector: Network Attack Complexity: Low Privileges Required: Low User Interaction: None Scope: Unchanged Confidentiality: High Integrity: High Availability: None

CWE ids for CVE-2021-27876

CWE-287 Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

Assigned by: nvd@nist.gov (Primary)

References for CVE-2021-27876

https://www.veritas.com/content/support/en_US/security/VTS21-001#issue2

Security Advisory for Backup Exec version 21.2 | Veritas™
Vendor Advisory
http://packetstormsecurity.com/files/168506/Veritas-Backup-Exec-Agent-Remote-Code-Execution.html

Veritas Backup Exec Agent Remote Code Execution ≈ Packet Storm
Exploit;Third Party Advisory;VDB Entry

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Vulnerability Details : CVE-2021-27876