Background exploitation KEV catalog Ransomware
CVE-2021-27878

Veritas Backup Exec Agent Command Execution Vulnerability

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…

CheckOps priority index
6.6/10 Patch within 7 days
Severity8.8
Probability2.4
Exploitation4/5

Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.

EPSS · today 24.0% higher than 97.8% of CVEs
CVSS 3.1 8.8 AC:L/AV:N/A:H/C:H/I:H/PR:L/S:U
Exploited for 1,306 days 07 Apr 2023
CISA due date 28 Apr 2023 for US federal agencies

Exploitation probability EPSS · FIRST

05010026 Sep05 Oct15 Oct24 Oct02 Nov
EPSS probability (%)Percentile among all CVEs

Exploitation signals 4 / 5

  • KEV catalog (CISA)07 Apr 2023
  • Exploited in EUVD (ENISA)07 Apr 2023
  • Used by ransomwareyes
  • EPSS above 10 %24.0%
  • No account, over the networkno

What to do

Fix

Apply the vendor’s fix as soon as it is available.

CISA guidance: Apply updates per vendor instructions.

Meanwhile

Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.

Manufacturers (CRA)

Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained

Description ENISA EUVD

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. The attacker could use one of these commands to execute an arbitrary command on the system using system privileges.

Affected products

Backup Exec Agent
Weaknesses (CWE)

Open source packages OSV

Affected libraries according to OSV, with fixed versions.

Timeline

  1. Published

  2. Exploitation reported (ENISA)

  3. Added to the KEV catalog

  4. CISA remediation due date

  5. EPSS peak: 24.0%

References

Other exploited vulnerabilities from the same vendor

  • CVE-2021-27877Veritas Backup Exec Agent Improper Authentication Vulnerability
    8.2 · Background exploitation
  • CVE-2021-27876Veritas Backup Exec Agent File Access Vulnerability
    6.0 · Background exploitation

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Sources: CISA KEV · ENISA EUVD · FIRST EPSS · OSV. Public data aggregated by CheckOps, updated automatically. Source texts remain the property of their authors. All exploited vulnerabilities