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

Static analysis result for SHA-256 fdf00af2636a0e87…

MALICIOUS

Office (OLE) / .XLSX

1.45 MB
MD5: 5c28a20ff81428e4038d11a4eca86729 SHA-1: 8dd4efc4906f1227589515da1ce37f1a12f09e37 SHA-256: fdf00af2636a0e8756bb4f8eece1dfe360127c96030ce3f4bbb1484909333de0
140 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file that contains an Equation Editor OLE object. This object appears to carry a payload, indicated by an anomaly in the Ole10Native stream size and entropy. The encryption with a default password and the presence of exploit carrier shapes further suggest malicious intent. The likely attack pattern involves luring a user to open the spreadsheet, triggering an exploit within the Equation Editor to download and execute a secondary payload.

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.