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

Static analysis result for SHA-256 53e1e896a6f72c7b…

MALICIOUS

Office (OLE) / .XLSX

1.15 MB
MD5: c492dd17e1220f76d25545280e8b352e SHA-1: 8ee1caea5f16ba15f2f550a07bcce4f0db498b90 SHA-256: 53e1e896a6f72c7b3799f518a00d37ee0c66fde7b7182f918d24d11112dfd04e
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 embedded OLE objects, specifically identified as an Equation Editor exploit carrier. This strongly suggests an attempt to leverage the Equation Editor vulnerability (CVE-2017-11882) to execute a malicious payload. The ClamAV detection as 'Xls.Downloader' further supports this, indicating a downloader functionality. No specific URLs or hashes were extracted, but the attack pattern is clear.

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.