Office (OLE) / .XLSX malware analysis — malicious · ff5b1175392d47a6

MALICIOUS

Office (OLE) / .XLSX

137.0 KB Created: 2011-02-09 21:46:00 Authoring application: Microsoft Excel

MD5: aabc6d9bf152cc78c3c3ab9d1729ac30 SHA-1: 31df3f58a0f8d5f38202544537566f832b533f00 SHA-256: ff5b1175392d47a6cb58dcc3bd607c0ef69e917c37dc7fcd9c2913d89afe9698

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical indicator of malicious intent. The document body text explicitly instructs the user to enable editing and content, a common social engineering tactic to bypass security warnings. The presence of the Auto_Open macro suggests the script will execute automatically upon opening the document, likely to download and execute a second-stage 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.

Filename	Kind	Source	Size
`xlm_macros.txt` `9caa967fa32a0ada90bc172742a951964d1118bee5a480feb60863a8e322a780`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	79530 bytes

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