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

Static analysis result for SHA-256 10c27f3c47a9fc32…

MALICIOUS

Office (OLE) / .XLSX

352.5 KB First seen: 2022-04-15
MD5: 18921cfd55e934b64d3f9d68a8b974ca SHA-1: 36d2d1805089ded968b01d3f7c6f4111231055b4 SHA-256: 10c27f3c47a9fc32634d1e60e38190046d49425d9a2487ec83c5ffc11f4f2828
160 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an encrypted Office document containing an Equation Editor OLE object. Heuristics indicate exploitation of CVE-2018-0798, a vulnerability in Equation Editor, which is commonly used to deliver malicious payloads. The encrypted nature and the presence of OLE objects suggest it's designed to bypass initial detection and execute arbitrary code upon opening.

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.