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

Static analysis result for SHA-256 e937a79ea1f44017…

MALICIOUS

Office (OLE) / .XLSX

167.0 KB Created: 2008-07-11 09:33:00 Authoring application: Microsoft Excel
MD5: 61dd0f78fba2050292257b18ba1f46e4 SHA-1: b81a96230d0a1394dda0cef35d552f28ad3fe943 SHA-256: e937a79ea1f44017a7aab30055fb6894c89fa7dc57a09a265f2b25926abad3ee
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell T1566.001 Spearphishing Attachment

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros with an Auto_Open entry, specifically utilizing the RUN function. This strongly suggests the macro is intended to execute a secondary payload. The presence of an Auto_Open macro in an Excel file is a common delivery mechanism for malware. The document body content is not human-readable and appears to be obfuscated or random data, providing no further context on the lure.

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
12c2ae25c750a158e5312c6b698ce1926552a8143478ad0d7b10ebbee81cf759
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 77890 bytes