Office (OLE) / .XLSX malware analysis — malicious · 38f2b7385b770c7f

MALICIOUS

Office (OLE) / .XLSX

130.5 KB Created: 2019-01-22 03:17:59 Authoring application: Microsoft Excel

MD5: 2a56433df2780dbc112368128586811b SHA-1: 2227815f4fabe16fd75f48ef491567230cfe31d3 SHA-256: 38f2b7385b770c7ff537ba3c6406a6e0f67440d71a10a7a6b709228929da2f36

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The macro sheet utilizes dangerous formula APIs, including the RUN function, suggesting it is designed to execute arbitrary commands. While the exact payload is not fully recoverable due to incomplete parsing, the presence of Auto_Open and the use of the RUN function strongly indicate a malicious execution flow.

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` `ded4ce127e76fd40e8cbee904a1b11e4920668f9d81afc81d2275f3ebaba8433`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	72318 bytes

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