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

Static analysis result for SHA-256 d29353c58d74a3b5…

MALICIOUS

Office (OLE) / .XLSX

1.17 MB
MD5: d9aebe616393eb7957959455ad819ab7 SHA-1: 25455a7ac0d05998c3909e5c659e7a4045309978 SHA-256: d29353c58d74a3b57551d854f64b1a7fdc1a5fba22a27a744dfce5997c718a27
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1203 Exploitation for Client Execution T1203 Exploitation for Client Execution

The sample is an encrypted OOXML file containing embedded OLE objects. The presence of Equation Editor objects with payload-like Ole10Native streams and a high entropy payload indicates the use of a CVE-2017-11882 exploit. The ClamAV detection as a Downloader suggests the 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.