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

Static analysis result for SHA-256 e5c3709f8c2bf4ef…

MALICIOUS

Office (OLE) / .XLSX

1.14 MB
MD5: aea5b1c74293b47417809d7228df1f6b SHA-1: 0b41815ab627175b9deba05ee748064d90e3d3b2 SHA-256: e5c3709f8c2bf4ef0fd19f5a33ae46d5cfbe38a92cefb90a357e18ff7f5c4d49
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1204.001 User Execution: Malicious Link T1204.002 User Execution: Malicious File T1204.002 User Execution: Mal File T1204.002 User Execution: Malicious File

The sample is an encrypted Office document using a default password, which is often used to bypass static analysis. It contains embedded OLE objects (oleObject1.bin) utilizing the Equation Editor exploit (CVE-2017-11882) Equation Editor OLE object. A ClamAV detection for a Downloader is a strong indicator of the same. No scripts were extracted from this sample.

Heuristics 4

  • 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.
  • 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.