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

Static analysis result for SHA-256 16f1fae4046b8f43…

MALICIOUS

Office (OLE) / .XLSX

1.25 MB
MD5: 259e2e7966bce39fd751d263610f51f9 SHA-1: ca4a7a41598dae3722c215b3a0e967c1ce33a2fe SHA-256: 16f1fae4046b8f4381575c900dbc0c17eeb1db6f98dadfe8ebf4580bf85b22b3
160 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an encrypted Excel spreadsheet that contains an embedded Equation Editor OLE object. This object exhibits an anomaly where it carries a payload-like Ole10Native stream, strongly suggesting it's designed to exploit a vulnerability for client execution. The default password encryption and the presence of embedded OLE objects point towards a malicious document intended to be delivered via spearphishing.

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.
  • 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 document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGE
    OLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007+, AES-128)).
  • 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.