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

Static analysis result for SHA-256 979d078e071b020a…

MALICIOUS

Office (OLE) / .XLSX

344.0 KB First seen: 2022-04-12
MD5: 7a4b75d95bd6eb473fb620863236847e SHA-1: 0c6d7621500b0c13992a04bebf9f34d232c255fd SHA-256: 979d078e071b020ac8a126851e57cfe99940a968f33cd356eb3db153f1b0a060
160 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an encrypted Office document containing an Equation Editor OLE object. Heuristics indicate it exploits CVE-2018-0798, a vulnerability in Equation Editor, to achieve code execution. The encrypted nature and the specific exploit vector suggest a downloader or initial access 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.