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

Static analysis result for SHA-256 a7b131be5c8ef7e1…

MALICIOUS

Office (OLE) / .XLSX

79.5 KB First seen: 2022-06-21
MD5: ed50508fb37851b7145c85231d5b8e5d SHA-1: 66832741946713a7e74a55a6ee43ca506b70f968 SHA-256: a7b131be5c8ef7e164f4e9916f455aa51918cee5740e846c50d51dc2a55c5d34
160 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an encrypted XLSX file that contains an Equation Editor OLE object. Heuristics indicate this object is anomalous and exploits CVE-2018-0798. This suggests the file is designed to leverage the Equation Editor vulnerability for initial execution, likely leading to the download and execution of a second-stage payload.

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.
  • Office document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGE
    OLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007, AES)).
  • 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.