Xls.Downloader.af2fa5c5d0587870-9978799-0 — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 2e056e63b52612a2…

MALICIOUS

Office (OLE) / .XLSX

1.21 MB
MD5: 7dc66b8ebb27218efc5fb2faceef2d99 SHA-1: 9ff667016204c815ea3669c9c2b0d3ac9fabfd86 SHA-256: 2e056e63b52612a2e8ef66a33adfb334320a854dc5b2f94b424a802a6271e52f
200 Risk Score

Malware Insights

Xls.Downloader.af2fa5c5d0587870-9978799-0 · confidence 95%

MITRE ATT&CK
T1204 Malicious File Execution T1566.001 Spearphishing Attachment

The file is an OOXML exploit carrier, indicated by the default-encrypted OOXML and the presence of an Equation Editor OLE object. This object contains a malformed Ole10Native stream, which is characteristic of exploit payloads. ClamAV detection further confirms its malicious nature as a downloader.

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.