Xls.Downloader.94c25b356b5a6cac-9978798-0 — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 7c0f414ad5f9c27c…

MALICIOUS

Office (OLE) / .XLSX

127.0 KB First seen: 2022-08-16
MD5: 2eff546c1ca6118d8fe41cf4a6f9119c SHA-1: b28e714e9b06b4c9d822155d3300e5e4c5495d8f SHA-256: 7c0f414ad5f9c27ce52cd182dae420750c88ebb679188e5af6d78ef6ed98a1b1
220 Risk Score

Malware Insights

Xls.Downloader.94c25b356b5a6cac-9978798-0 · confidence 95%

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious File T1566 Phishing T1566.001 Spearphishing Attachment T1059 Command and Scripting Interpreter

This Excel file is password-encrypted and contains an embedded Equation Editor OLE object. Heuristics indicate it is an exploit carrier for CVE-2018-0798, a vulnerability in Microsoft Equation Editor. The file is detected by ClamAV as a downloader, suggesting it is intended to fetch and execute a secondary payload.

Heuristics 6

  • 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.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Default-encrypted OOXML contains embedded Equation Editor data with anomalous native stream bytes consistent with a CVE-2018-0798-style exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like.
  • ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.94c25b356b5a6cac-9978798-0
  • 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 document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGE
    OLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007, AES)).
  • 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.

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