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

Static analysis result for SHA-256 9508d3c18d753430…

MALICIOUS

Office (OLE) / .XLSX

1.14 MB
MD5: 410f43574e0f0e05d2d59f42b8a3d87a SHA-1: 066f5e64acd3fe8f7395ee38563bbfa04844ea62 SHA-256: 9508d3c18d753430376df4c464c4bb82991d9fc4556b3dee0a5ff77794ca9f2b
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The file is an encrypted Excel spreadsheet that contains an embedded Equation Editor object. This object is known to be used as a carrier for exploits, and the anomaly detected in the Ole10Native stream suggests it contains a payload. ClamAV detection confirms this is a downloader. The default password encryption and the presence of an exploit carrier point to a malicious document designed to deliver 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.