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

Static analysis result for SHA-256 20a8cd5647ad83d3…

MALICIOUS

Office (OLE) / .XLSX

2.09 MB
MD5: 91cfe8c22dc8525e8f497e21240825e4 SHA-1: 5d1fb3d98e532528431729f45957807311923695 SHA-256: 20a8cd5647ad83d3f4574545fa1447e35947e4dec77ee4505940b81d23a0ba34
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1566.001 Spearphishing Attachment

The sample is an encrypted Office XLSX file that contains an embedded Equation Editor OLE object. Heuristics indicate that this object is anomalous and likely carries a payload, specifically targeting CVE-2018-0798. The encryption with a default password and the presence of an exploit carrier shape further suggest malicious intent. The attack pattern involves exploiting a vulnerability within the Equation Editor to achieve code execution.

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.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Default-encrypted OOXML contains embedded Equation Editor data with anomalous native stream bytes consistent with a CVE-2018-0798-style exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like.
  • 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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