MALICIOUS
240
Risk Score
Malware Insights
MITRE ATT&CK
T1566.001 Spearphishing Attachment
T1204.002 Malicious File
The sample is a password-encrypted XLSX file identified by ClamAV as Doc.Downloader.Formbook. The encryption and the presence of an Equation Editor OLE object within the OOXML structure indicate it's designed to exploit vulnerabilities, likely to download and execute a secondary payload. The file's SHA256 hash is included as a primary IOC.
Heuristics 6
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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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Encrypted Office package with CFB FAT corruption critical OLE_ENCRYPTED_AND_MALFORMEDEncrypted-package shape co-occurs with FAT-chain corruption — the documented combined evasion form.
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ClamAV: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0 critical CLAMAV_DETECTIONClamAV detected this file as malware: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0
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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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Office document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGEOLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007, AES)).
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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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