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

Static analysis result for SHA-256 573325c6bff289c7…

MALICIOUS

Office (OLE) / .XLSX

1.12 MB
MD5: c7b276fb03872d1462e0392e625f34af SHA-1: 0bb5b579b400e8e35d9caac6174c434c21982593 SHA-256: 573325c6bff289c71b457ce03f1e0aee2737adffd05011a3c3de63a6b3adf017
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059 Command and Scripting Interpreter T1203 Exploitation for Client Execution

The sample is an encrypted OOXML file containing embedded OLE objects. The presence of an Equation Editor object with a payload-like Ole10Native stream anomaly suggests the use of a CVE-2017-11882 style exploit to achieve remote code execution. ClamAV detection as a Downloader indicates the likely intent is to fetch and execute 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.
  • 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.
  • 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.