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

Static analysis result for SHA-256 a841562af528c284…

MALICIOUS

Office (OLE) / .XLSX

1.20 MB
MD5: bc16b8416398b0fb0026be982e81a903 SHA-1: f36d2cd6edf8f951179530539e009982bf0217de SHA-256: a841562af528c284fe0e30a11862603d4c97f16cc0f81113d85fcc72d7ff9f6d
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment T1027 Obfuscated Files or Information

The sample is an encrypted OOXML file that uses the 'VelvetSweatshop' default password to bypass static analysis. It contains an embedded OLE object with the Equation Editor CLSID and a malformed Ole10Native stream, which is characteristic of the CVE-2017-11882 exploit. No scripts were extracted from this sample, but the structural evidence strongly indicates an exploit-based delivery mechanism.

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.