Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 9ad0c5a8e7f99519…

MALICIOUS

Office (OLE)

268.0 KB Created: 2021-02-06 22:23:31 Authoring application: Microsoft Excel
MD5: cd387c0b2b2983b93f2efcc8f16f86e5 SHA-1: 1266a4f4bec32a470ba33305ca60aea74aaa76be SHA-256: 9ad0c5a8e7f99519411153dd55758bec19abc0dbe8673128e0472d18bb2d9685
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 PowerShell T1204.002 Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro designed to execute automatically upon opening. The extracted macro script reveals a PowerShell command constructed using string concatenation: 'powersh' & CHAR(D108) & 'll -w 1 (nEw-oB`jecT Ne' + CHAR(116) + CHAR(46) + CHAR(87) + CHAR(101) + 'bCL`I`eNT).('D' + CHAR(111) + CHAR(119) + 'n'+'

Heuristics 3

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
f176c2ba5b770c3fdeadaa477a1ec5c99c104e120d117aed7ea23bc000c84ea6		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1242 bytes

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