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

Static analysis result for SHA-256 aa8e15db3c478992…

MALICIOUS

Office (OLE) / .XLSX

1.24 MB
MD5: b0aa33fab7a24bd78056ef69fa0e303f SHA-1: 85c877a5529a993ef2da8256cc1e6707feb2df40 SHA-256: aa8e15db3c4789920ece395319c312b19f996099651f43ed9997e8b52b0fb100
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File Execution: User Execution of Malicious Code

The file is an encrypted Excel spreadsheet that utilizes a default password, a common technique for obfuscating malicious content. High-severity heuristics indicate the presence of an Equation Editor OLE object, which is frequently used to deliver malware. 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.