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CriticalCISA KEVExploited in the wildPublic exploit

Unauthenticated Command Injection in Cleo Harmony, VLTrader, and LexiCom Autorun Directory

IdentifiersCVE-2024-55956CWE-78

CVE-2024-55956 affects Cleo Harmony, VLTrader, and LexiCom before version 5.8.0.24. According to the provided content, an unauthenticated attacker can import and execute arbitrary Bash or PowerShell commands on the underlying host by leveraging the default settings of the Autorun directory. Supporting reporting also characterizes the issue as an unauthenticated arbitrary file-write condition associated with the /Synchronization endpoint, which can be used to place attacker-controlled content into locations that are subsequently executed via Autorun behavior. The vulnerability was observed in the wild in late 2024 and used in compromises of Cleo managed file transfer deployments, including deployment of the Java backdoor 'Malichus.'

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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 permits unauthenticated remote command execution on the host system running the affected Cleo product. In observed intrusions, this enabled attackers to deploy persistent backdoors, execute follow-on commands, steal data, and obtain further access into victim environments. Reporting in the provided content links exploitation to large-scale data-theft and extortion campaigns, including ransomware-associated operations.

Mitigation

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

If immediate patching is not possible, reduce exposure by restricting or disabling untrusted access to affected Cleo services, especially any externally reachable /Synchronization functionality, and by preventing abuse of the Autorun directory where operationally feasible. Review and harden default Autorun behavior, monitor for unexpected file creation and execution in Autorun-related paths, and alert on suspicious Bash or PowerShell invocation by the Cleo application. Network segmentation and limiting internet exposure of Cleo MFT systems can reduce exploitability, but the provided content indicates upgrading to 5.8.0.24 is the primary corrective action.

Remediation

Patch, then assume compromise.

Upgrade Cleo Harmony, VLTrader, and LexiCom to version 5.8.0.24 or later, as the provided content states this version fixes CVE-2024-55956. Because exploitation has been observed in the wild, organizations should also review systems for indicators of compromise, including unauthorized files written via the /Synchronization functionality, suspicious content in the Autorun directory, unexpected Bash or PowerShell execution, and presence of the Malichus Java backdoor or other persistence artifacts. If compromise is suspected, perform incident response actions including containment, credential rotation, and forensic review of affected hosts.
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
CleoHarmonyapplication
CleoLexicomapplication
CleoVltraderapplication

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

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

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Threat actor evidence6

Every observed campaign linking this CVE to a named adversary.

Associated malware7

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.