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

Static analysis result for SHA-256 e73ff0447bc7ca92…

MALICIOUS

Office (OLE) / .XLSX

1.14 MB
MD5: 8fedaeae8d1bce3d05bc16310788b02c SHA-1: 2428e3202368f503f98d31586976522762b666f8 SHA-256: e73ff0447bc7ca92c1738a8fd614eb5ad63d59b15661dee11b1ca79db9f0f1d8
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1566 Phishing T1204.002 Malicious File: User Execution T1059 Command and Scripting Interpreter

The file is an encrypted Excel spreadsheet that utilizes embedded OLE objects, specifically exploiting the Equation Editor vulnerability. This is strongly indicated by the 'OLE_EQUATION_EDITOR' and 'OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY' heuristics. The 'OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPE' heuristic further suggests it's designed as an exploit carrier. ClamAV detection confirms its malicious nature as a downloader.

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.

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