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CriticalCISA KEVExploited in the wildPublic exploit

Authentication bypass in Veritas Backup Exec Agent via legacy SHA authentication

IdentifiersCVE-2021-27877CWE-287

CVE-2021-27877 affects Veritas Backup Exec before version 21.2. The product supported multiple authentication schemes, including a legacy SHA-based authentication mechanism. Although this scheme was no longer used in current product operation, it had not been disabled. A remote attacker could exploit the still-enabled legacy authentication path to gain unauthorized access to a Backup Exec Agent and then execute privileged commands on that agent.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an unauthenticated remote attacker to bypass intended authentication controls, obtain unauthorized access to a Veritas Backup Exec Agent, and execute privileged commands. This can enable compromise of the agent host, abuse of backup infrastructure, and potentially follow-on actions affecting confidentiality, integrity, and availability of protected systems and data.

Mitigation

If you can’t patch tonight, do this now.

Until patching is completed, reduce exposure of Backup Exec Agents to untrusted networks, restrict network access to agent services to only authorized Backup Exec infrastructure and administrative hosts, and monitor for unexpected authentication attempts or privileged command execution against agents. Segmentation and host-based access controls can reduce the likelihood of remote exploitation.

Remediation

Patch, then assume compromise.

Upgrade Veritas Backup Exec to version 21.2 or later, where the obsolete SHA authentication scheme is no longer exposed for exploitation. If vendor guidance is available in the environment, apply the corresponding Veritas security update or hotfix addressing CVE-2021-27877.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Veritas TechnologiesBackup Execapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware1

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity2

Community discussion across Reddit, Mastodon, and other social sources.