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

Static analysis result for SHA-256 05c4ef24468ae00a…

MALICIOUS

Office (OLE) / .XLSX

1.22 MB
MD5: f378e433fd7e12404845b339e207fbc8 SHA-1: a7696944bf20bcd237d9b1d33f3f9a863a488ea4 SHA-256: 05c4ef24468ae00a47764f92984c36a6ca933dcdbd90fd409ba5327caf43b915
220 Risk Score

Malware Insights

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

The file is an encrypted Office document containing an embedded Equation Editor OLE object, a known carrier for exploits. The 'OLE_EQUATION_EDITOR' and 'OLE_ENCRYPTED_AND_MALFORMED' heuristics indicate this object is likely used to exploit a vulnerability, leading to the execution of a secondary payload. The document's encryption and malformed structure further support its role as an exploit carrier.

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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