Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 37fffcbacca59290…

MALICIOUS

Office (OLE) / .XLSX

1.17 MB
MD5: 870a4c72bccd58de144c7b845d56c626 SHA-1: 482681f75180bbb1286e1f93ce44dfae0b6b0007 SHA-256: 37fffcbacca59290a7a3b6271ebf475a50b9e17eba113459cfc00508a7268b68
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link

The file is an Excel spreadsheet that is encrypted with a default password and contains an embedded Equation Editor OLE object. This object appears to carry a payload, indicated by an anomalous Ole10Native stream. ClamAV identifies this as a downloader. The combination of these factors strongly suggests the file is designed to exploit a vulnerability, likely via the Equation Editor, to download and execute a second-stage payload.

Heuristics 5

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Default-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.
  • ClamAV: Xls.Downloader.af2fa5c5d0587870-9978799-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.af2fa5c5d0587870-9978799-0
  • Default-encrypted OOXML exploit carrier layout high OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPE
    Default-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.
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Default-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.
  • Office OOXML encrypted with default VelvetSweatshop password medium OFFICE_DEFAULT_PASSWORD_ENCRYPTED_OOXML
    OLE 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.