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

Static analysis result for SHA-256 ebb1a46ca25e0fc8…

MALICIOUS

Office (OLE) / .XLSX

42.0 KB Created: 2020-09-28 00:53:43 Authoring application: Microsoft Excel
MD5: fbea7482e267dda8d5c68218419c7caa SHA-1: d1327698fcd53fd188e85b0c47f6ccc39b26fe8a SHA-256: ebb1a46ca25e0fc83db0ddb42f80be7882f13e2d48c489c7b2bcec8a69b97c03
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of the 'RUN' function within these macros suggests the execution of arbitrary commands, likely to download and run a secondary payload. While the exact payload or delivery mechanism is not fully detailed, the macro sheet's structure and the use of dangerous functions point towards a downloader or initial access stage.

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
9881dc72b11a6676d5240d63e317838a8da4d730409608479ad25b50ccd9cb60		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8002 bytes

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