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

Static analysis result for SHA-256 dc4c8d4c7836e303…

MALICIOUS

Office (OLE) / .XLSX

1.21 MB
MD5: 223cd0e05425a90526a13c19d26ab2f1 SHA-1: 5749f2771d0fd50d0d57ab871fc0d8b3137c6c37 SHA-256: dc4c8d4c7836e303a096dc35c692d20dc92c1bf99cae8597c340d14fbf8119a5
140 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file that contains an Equation Editor OLE object. This object exhibits anomalies in its Ole10Native stream, suggesting it is designed to carry a malicious payload. The presence of the Equation Editor OLE object is a strong indicator of exploit delivery, commonly associated with the Equation Editor vulnerability (CVE-2017-11882).

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.