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

Static analysis result for SHA-256 2b82ac8a7dce0dc9…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:44:57 Authoring application: Microsoft Excel
MD5: 010340c50bd9b6b7cabbf257776923bc SHA-1: e0ec56bf577356754ee33644c166aecb06b81057 SHA-256: 2b82ac8a7dce0dc9ad4af88f1f1c857b3b90b959c90c202f3439e8bf41d8da25
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical heuristic firing. This indicates the macro will execute automatically upon opening the workbook. The presence of dangerous formula APIs like 'RUN' further suggests the macro is designed to execute arbitrary commands. While the specific commands are not fully visible due to truncation, the overall pattern points to a downloader or initial execution stage for a malicious payload.

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
c942efffeeaf27a592cf32928f1c05465796afd5a68f5e3ea12f5bff585a6b30
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6831 bytes