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

Static analysis result for SHA-256 e992951d71d4d84d…

MALICIOUS

Office (OLE) / .XLSX

1.27 MB
MD5: da750029bfc8d0fd52d52b10812d8cfc SHA-1: e77aaaf9643060b68a84b7c749661baeea038ba0 SHA-256: e992951d71d4d84d63cfa6bfbb4aaeddecd3ed2970a93a1a3e9df56720ae78e1
160 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment T1059 Command and Scripting Interpreter

The sample is a default-encrypted OOXML file containing an Equation Editor OLE object, which is a high-signal indicator of exploits targeting CVE-2017-11882 or similar vulnerabilities. ClamAV's detection as a downloader is a result of thes specific exploit delivery mechanism. No scripts were extracted from this sample, but the exploit's intent is to execute arbitrary code via the OLE object.

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.