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

Static analysis result for SHA-256 e5501150e796ff52…

MALICIOUS

Office (OLE) / .XLSX

1.23 MB
MD5: e4d36a35ae307475874edeac6177e6bd SHA-1: 1cabf6f2b24fa3b7c0a7735ff059aa30da58bac5 SHA-256: e5501150e796ff528bd809d71380dd8214699e05450c6d083dd07cfffe8efbb6
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1566 Phishing T1204.002 Malicious File: User Execution

The sample is an encrypted Excel file that contains embedded OLE objects, specifically identified as an Equation Editor exploit carrier. This strongly suggests an attempt to leverage the Equation Editor vulnerability (CVE-2017-11882) to execute a payload. The ClamAV detection as 'Xls.Downloader' further supports this, indicating a downloader functionality. No specific IOCs like URLs or hashes were extracted, but the attack pattern is clear.

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.