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

Static analysis result for SHA-256 c85be461c71e3ea0…

MALICIOUS

Office (OLE) / .XLSX

554.0 KB
MD5: f76ce4db822731292d0f771d95f2605a SHA-1: a17c412a138687d79fb31aaa7d130fe61dffab6b SHA-256: c85be461c71e3ea06d59b1e1ba431c349cbe8d587e7844b739eebb9c7d5125cf
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1204.002 Malicious File: User Execution T1059 Command and Scripting Interpreter

The sample is a default-encrypted OOXML file containing an Equation Editor OLE object. High-severity heuristics indicate this object exploits CVE-2018-0798, a vulnerability in Equation Editor. This exploit is designed to download and execute a secondary payload, as indicated by the ClamAV detection name 'Xls.Downloader'.

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.
  • ClamAV: Xls.Downloader.af2fa5c5d0587870-9978799-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.af2fa5c5d0587870-9978799-0
  • 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 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.