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

Static analysis result for SHA-256 9f2e08425fbeaaea…

MALICIOUS

Office (OLE) / .XLSX

1.17 MB
MD5: 1750cc351256aa28d74e6b77985e8b8c SHA-1: 3de8ea8dc223217c7068e2edd6bed6e618f980d2 SHA-256: 9f2e08425fbeaaea9d92e472bc4e6b9dcfb578fdcf4dab4f6169490ad366be3c
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter T1071.001 Application Layer Compromise T1566.001 Privilege Escalation T1087 System Execution T1489 Drive Information

The file utilizes a standard OOXML exploit delivery technique, employing a default-encrypted Excel package to hide malicious code. The presence of the Equation Editor CLSID (CVE-2017-11882) within a high-entropy Ole10Native stream strongly suggests an attempt to exploit this vulnerability. The ClamAV detection confirms the file's malicious nature. The decrypted package reveals further obfuscation and likely contains a downloader or payload. The high entropy stream and malformed package sizing are key indicators of an exploit attempt.

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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