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

Static analysis result for SHA-256 03cb9990038aa907…

MALICIOUS

Office (OLE) / .XLSX

1.05 MB
MD5: cede8c1c9af0b1adb14fb1271ad9043d SHA-1: c6baef784bcf353ea2d8bf046015114b2278deb8 SHA-256: 03cb9990038aa9076d4fb5e8870847378578863f0e477f75347db015123fc6da
160 Risk Score

Malware Insights

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

The file is an encrypted Office document containing an Equation Editor OLE object, which is a known carrier for exploits. The presence of an anomalous Ole10Native stream within the Equation Editor object strongly suggests it is being used to deliver a second-stage payload. The exploitation of the Equation Editor is indicative of the Exploitation for Client Execution (T1203) technique, and the document itself likely arrived via Spearphishing Attachment (T1566.001).

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.

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