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

Static analysis result for SHA-256 a688a85e74de4042…

MALICIOUS

Office (OLE) / .XLSX

1.19 MB
MD5: 9dcf1ee2b34aed3acd5d85fe02ab9f74 SHA-1: 230fc13bbeb2d24c47647e3de2240e765f072d32 SHA-256: a688a85e74de4042e43a2fd30cf7072c082170b19f86f44df5895f79bacab8b8
140 Risk Score

Malware Insights

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

The file is an encrypted OOXML document that contains an embedded Equation Editor OLE object. This object exhibits anomalies indicative of a payload, specifically an impossible Ole10Native header with a declared inner size far exceeding the actual stream size. This strongly suggests the Equation Editor is being used as a carrier for a malicious exploit, likely targeting a known vulnerability.

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.