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CriticalCISA KEVExploited in the wildPublic exploit

OS Command Injection in Accellion FTA admin endpoints

IdentifiersCVE-2021-27104CWE-78· Improper Neutralization of Special…

CVE-2021-27104 is an operating system command injection vulnerability in Accellion File Transfer Appliance (FTA). According to the provided content, the flaw affects FTA 9_12_370 and earlier and can be triggered via a crafted POST request sent to various FTA administrative endpoints. Multiple sources in the content characterize the issue as remotely exploitable and unauthenticated. Successful exploitation causes attacker-controlled input to be executed as OS commands on the underlying appliance. The vulnerability was one of several Accellion FTA flaws exploited in real-world intrusions associated with data theft campaigns.

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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 remote execution of operating system commands on the vulnerable Accellion FTA appliance. In observed campaigns, exploitation of Accellion FTA vulnerabilities enabled deployment of web shells, access to and exfiltration of files from the appliance, and potentially further intrusion activity into victim environments. The content specifically notes victim data access and possible pivoting into victim networks.

Mitigation

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

If immediate patching or migration is not possible, isolate or block internet access to systems hosting Accellion FTA, prioritize incident investigation on exposed appliances, collect forensic images if compromise is suspected, audit FTA accounts and credentials, and reset security tokens including the W1 encryption token due to possible exposure in related Accellion exploitation activity. Given active exploitation and product end-of-life, mitigation should be treated only as temporary pending upgrade or replacement.

Remediation

Patch, then assume compromise.

Upgrade Accellion FTA to a fixed release. The primary description in the content states the fixed version is FTA_9_12_380 and later. Additional advisory material in the content recommends updating Accellion FTA to FTA_9_12_432 or later as part of the broader remediation for the exploited FTA vulnerability set. Because Accellion FTA reached end of life on April 30, 2021, organizations should migrate to a supported file-sharing platform as directed by the vendor.
PUBLIC EXPLOITS

Exploits

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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
AccellionFtaapplication

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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 malware2

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 activity

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