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

Static analysis result for SHA-256 f8ff829b2fbab285…

MALICIOUS

Office (OLE) / .XLSX

1.15 MB
MD5: 3cfaf0e919172d1c6e1ef7e766b2fb36 SHA-1: 47f3d29e7daaed6b0b6bdc205e27ff0f971f247c SHA-256: f8ff829b2fbab28557c00eb6267dabb8918b12644f9daeabd1af0cd7d01c9034
140 Risk Score

Malware Insights

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

The sample is an encrypted Excel file that utilizes a default password, a common technique to evade initial static analysis. It contains an Equation Editor OLE object, which is frequently used to deliver exploits. The presence of an anomalous Ole10Native stream within the Equation Editor object suggests it is designed to carry a malicious payload, likely exploiting vulnerabilities within the Equation Editor itself.

Heuristics 4

  • 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.
  • 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.