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

Static analysis result for SHA-256 bbb331fee4b97b79…

MALICIOUS

Office (OLE) / .XLSX

1.26 MB
MD5: 4f5491734137cfe3c5a8ba67396ca130 SHA-1: 2bb409a50fe1b130f47e163f369e5a24a0d70ec1 SHA-256: bbb331fee4b97b790b6be4c064e60d036fa802e7b333bd1e92db70465ec7db55
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an encrypted XLSX file that contains an embedded Equation Editor OLE object. This object exhibits anomalies in its Ole10Native stream, suggesting it's designed to carry a malicious payload. The presence of the Equation Editor OLE object is a strong indicator of exploit delivery, commonly used to drop further malware.

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.