Office (OLE) / .XLSX malware analysis — malicious · 8555ab6a75f673c3

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:39:56 Authoring application: Microsoft Excel

MD5: fd7055fa4fb74bf946f73e2cd503778a SHA-1: 18408f2dda4965a97c757f2f9198a4f6257f75fc SHA-256: 8555ab6a75f673c3214174a8868ef513be5ef5371f05b5f3dec482d527aae07f

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating automatic execution. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary code. While the exact payload is not discernible from the provided evidence, the Auto_Open function strongly implies an attempt to run a second-stage exploit or downloader.

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` `c198d22e4fb4af983f1f180e045adcf3d14a04990929054a45d53cd053a8b17d`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6394 bytes

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