Office (OLE) / .XLSX malware analysis — malicious · 79c817310ea639d4

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:43:07 Authoring application: Microsoft Excel

MD5: ce8da2ca317b3163d811447d1127912b SHA-1: 58d002b3f872b2fd74961177e1399bdf2a06b06c SHA-256: 79c817310ea639d4f76e5e21c3d76badd493ff85ed71048e184db0acc921ce0b

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 known technique for executing malicious code upon opening the workbook. The critical heuristic firings indicate the presence of dangerous formula APIs within the Auto_Open macro, suggesting it's designed to run commands. No specific family could be identified, and no external IOCs like URLs or hashes were extracted.

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` `dcfd41fea92d42205f591c6767b6664b02381df15bab788ebbd73b66e2515bdd`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6658 bytes

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