MALICIOUS
200
Risk Score
Malware Insights
MITRE ATT&CK
T1204.002 User Execution: Malicious File
T1059 Command and Scripting Interpreter
T1203 Exploitation for Client Execution
The sample is an encrypted XLSX file using a default password, which is often used to bypass static analysis. It contains Equation Editor OLE objects with anomalous Ole10Native streams, indicating a known exploit pattern (likely CVE-2017-11882). The ClamAV detection specifically identifies it as a downloader, suggesting the final stage is to fetch and execute a second-stage payload.
Heuristics 5
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Equation Editor OLE object high OLE_EQUATION_EDITORDefault-encrypted OOXML embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
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ClamAV: Xls.Downloader.af2fa5c5d0587870-9978799-0 critical CLAMAV_DETECTIONClamAV detected this file as malware: Xls.Downloader.af2fa5c5d0587870-9978799-0
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Default-encrypted OOXML exploit carrier layout high OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPEDefault-password encrypted OOXML package contains embedded OLE object parts and additional activation/decoy parts. This layout is common in malicious Excel exploit delivery and requires inspecting the decrypted package.
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Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALYDefault-encrypted OOXML embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is exploit-shaped Equation/OLE payload evidence.
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Office OOXML encrypted with default VelvetSweatshop password medium OFFICE_DEFAULT_PASSWORD_ENCRYPTED_OOXMLOLE EncryptedPackage decrypts with Excel's built-in VelvetSweatshop password. Office opens this transparently, and malware uses it to hide OOXML exploit parts from scanners that only inspect the outer OLE container.
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