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

Static analysis result for SHA-256 b916ee9ac5a31baa…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:39:57 Authoring application: Microsoft Excel First seen: 2023-03-30
MD5: e54f72b1de3e97efe28c97470d3b00f3 SHA-1: 1eeed3b2fd10ff8f2b61237d23648e086fca677d SHA-256: b916ee9ac5a31baa984fa1f21caa27f09e4441862a49de9173c5ee69866794c1
140 Risk Score

Malware Insights

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

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a known technique for executing malicious code upon opening the workbook. The `RUN=0` flag suggests the macro is designed to execute a command, likely a downloader for a second-stage payload. No specific IOCs were extracted, but the technique itself is highly indicative of malicious intent.

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
81448c2275150996c91e16a825cbc2e15df97746c4a9a929171be59e5176413d
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6698 bytes