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

Static analysis result for SHA-256 4a5c10a7e9ec7b65…

MALICIOUS

Office (OLE) / .XLSX

1.44 MB
MD5: 75c48b4392ae795beeb0317bfaef77bd SHA-1: 8e3e8daaa18cb3cf0e3b73e90ecbd297c9d5e1ee SHA-256: 4a5c10a7e9ec7b65f8605186726d4861c5bc96870204e12eb260ebd841e7aedb
140 Risk Score

Malware Insights

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

The sample is an encrypted OOXML file that utilizes default password encryption, a common technique for obfuscation. High-severity heuristics indicate the presence of an Equation Editor OLE object, which is known to be exploited. The anomaly in the Ole10Native stream within the Equation Editor object suggests it carries a malicious payload, likely intended to exploit a vulnerability and download a second-stage 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.