Office (OLE) / .XLSX malware analysis — malicious · 1e2a325d2e94b681

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:41:48 Authoring application: Microsoft Excel

MD5: 2db4fb82533191b3601c2ccfff3d9e3a SHA-1: 9bd03ccd291651f6ad60d79b1b9a6c581bd26c07 SHA-256: 1e2a325d2e94b681c2605d804d29ab6ce185f8d3656ecb3e4f1b6835a6226ed3

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

This XLSX file contains Excel 4.0 macros, specifically an Auto_Open defined name. The critical heuristic firings indicate that this macro sheet contains dangerous formula APIs, including the RUN function, which is commonly used to execute arbitrary commands. The presence of the Auto_Open function strongly suggests that the macro will execute automatically upon opening the file, 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` `ee185cd4ac5a41b244265f6f88d225ddd746b31f744970abca94eaf6e633abb0`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6685 bytes

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