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

Static analysis result for SHA-256 f9b386251c385985…

MALICIOUS

Office (OLE) / .XLSX

1.36 MB
MD5: 39ed41e4dbd89c5529f95aa7c4c91d78 SHA-1: abd798c85f51425fa98e074c94618242d140a0eb SHA-256: f9b386251c385985dbc89ee5ca5313375b6c10a4721256d2ed12cd103759a804
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter T1071.001 Application Layer Compromise T1566.001 Privilege Escalation T1083 System Information Discovery

The file's structure, including the default-encrypted OOXML package, the presence of the Equation Editor OLE object (with a malformed Ole10Native stream), and the use of a password-protected Excel file, strongly suggests a macro-based dropper. The Equation Editor CLSID, linked to known vulnerabilities (CVE-2017-11882, CVE-2018-0802), indicates an attempt to exploit these vulnerabilities. The large, high-entropy stream within the Equation Editor object is a key indicator of a payload, likely designed to execute code upon opening the document. The decryption process and subsequent exploitation of the Equation Editor component are consistent with a classic Equation Editor-based exploit.

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.

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