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

Static analysis result for SHA-256 1c02e78f3a7c4877…

MALICIOUS

Office (OLE) / .XLSX

553.6 KB
MD5: c33594d164e9f797d99f6161199f46ab SHA-1: 5d69c96d9b8c44386d56093b9f2b0bf2810885f2 SHA-256: 1c02e78f3a7c4877f770d291e341f1c25bfc824161d0a4101a8a061c4c1e40e8
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1566.002 Spearphishing Attachment

The file is an encrypted Excel spreadsheet that utilizes a default password, a common technique for obfuscating malicious content. It contains an embedded Equation Editor OLE object, which is known to be exploited via CVE-2018-0798. ClamAV identifies this as Xls.Downloader.af2fa5c5d0587870-9978799-0, indicating it functions as a downloader. The presence of the Equation Editor exploit carrier suggests the primary purpose is to download 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.
  • 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.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.

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