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

Static analysis result for SHA-256 41dc6f104f366a85…

MALICIOUS

Office (OLE) / .XLSX

1.26 MB
MD5: 71d41ee17c63a2f763ec84ae4d0a5319 SHA-1: f1955db264e1e834e66be559891c6d97155a7211 SHA-256: 41dc6f104f366a85ae7bdc3c7bf566598dbdfcdcdd995fba68318cdbf5d44459
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter T1071.001 Application Layer Compromise T1566.001 Privilege Escalation T1083 System Modification T1071.002 Application User Management

The file's structure, including the default-encrypted OOXML package, the presence of the Equation Editor component (CVE-2017-11882), and the ClamAV detection, strongly indicate a malicious intent. The ClamAV detection confirms the file is flagged as malware. The exploitation likely involves leveraging the Equation Editor's vulnerabilities to achieve arbitrary code execution, potentially downloading and executing a secondary payload. The use of a default-encrypted package is a common tactic to bypass initial security checks.

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.

Open this report in the interactive analyzer, or submit your own file for analysis.