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

Static analysis result for SHA-256 671e54f81f4ddc50…

MALICIOUS

Office (OLE) / .XLSX

1.16 MB
MD5: 95d104ec7c7cd042ca681e0ed093da1a SHA-1: 04feae10696b123e43d9884f9dcb4f10ff26b2ee SHA-256: 671e54f81f4ddc50be5ce1d0ed729bb95d18f0e280d739d3975b1aaeaca38bf2
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an encrypted Office document containing an Equation Editor OLE object. This object carries a payload-like Ole10Native stream, indicating it's likely used to exploit a vulnerability such as CVE-2017-11882 for client execution. The document's encrypted nature and the presence of an exploit carrier suggest it was delivered as a malicious attachment.

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.
  • Encrypted Office package with CFB FAT corruption critical OLE_ENCRYPTED_AND_MALFORMED
    Encrypted-package shape co-occurs with FAT-chain corruption — the documented combined evasion form.
  • 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 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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