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

Static analysis result for SHA-256 fba36193cf396bc4…

MALICIOUS

Office (OLE) / .XLSX

228.6 KB
MD5: 58303fe287d797952b310624a55f393b SHA-1: 7ea740858d3b8bdbc281b4d08c95d90a17c286e7 SHA-256: fba36193cf396bc45ababa1fb8419398359c1f97d7d3afd5a8beaec9224f4bd8
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1204.001 User Execution: Malicious Link T1204.002 User Execution: Malicious File T1204.002 Pishing: Malicious Attachment T1204.002 User Execution: Malicious shellcode shellcode T1204.002 User Execution: Malicious File T1204.002 User Execution: Malicious File

The sample is a password-encrypted OOXML file using the default VelvetSweatshop password, which is common in malware delivery. It contains an embedded OLE object (xl/embeddings/oleObject1.bin) that triggers CVE-2018-0798 in the Equation Editor, as evidenced by the high entropy and anomalous native stream. The encryption and OLE FAT chain loop corruption are likely intended to evade detection by security products.

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.
  • 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.
  • 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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