Office (OLE) / .XLS malware analysis — malicious · 73b388494988720a

MALICIOUS

Office (OLE) / .XLS

40.5 KB Created: 2020-11-13 16:16:25 Authoring application: Microsoft Excel

MD5: e7cc398798b648228802277ea6c05250 SHA-1: fa37eba824bec5c411fc2833e92d0695e6501285 SHA-256: 73b388494988720ac1397f2ae765866a6a1a8fa863869659e980f93b82808535

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel XLS document containing Excel 4.0 macros, specifically an Auto_Open defined name. This indicates an attempt to automatically execute code upon opening the document. The critical heuristic firing for 'XLM Auto_Open with dangerous formula APIs' suggests the macro attempts to call functions that can lead to arbitrary code execution, likely to download and run 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` `c81188d9a253c2ade61065f7a817aa4300b07902ae3a57c3577789b0ef8d3727`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	9291 bytes

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