Office (OLE) / .XLSX malware analysis — malicious · 696fa29c7363ed50

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:40:50 Authoring application: Microsoft Excel

MD5: b8b15e0f9dcc872c1323bac3460ce28e SHA-1: 96827ff80fd45d0ef0f2e59603263fc659338dae SHA-256: 696fa29c7363ed5079e3e969460a6d9fb9ceec7c331a3226808631678d9c29d4

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open defined name, which is a known method for executing malicious code. The macro sheet contains formulas that call dangerous APIs, including 'RUN', suggesting an attempt to execute arbitrary commands. The presence of an Auto_Open entry strongly implies that the macro will execute automatically upon opening the workbook.

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` `f77fad759952d623330e3d3b033f478bd593b27cbcb4114d3e9eb57c552dae0f`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6626 bytes

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