Office (OLE) / .XLS malware analysis — malicious · a351d23b753cdf5a

MALICIOUS

Office (OLE) / .XLS

36.0 KB Created: 2021-02-16 17:07:08 Authoring application: Microsoft Excel

MD5: 5d019b38630d3dc9317de5a0c471f94d SHA-1: 5d88e750961481cd2a3cada842843a06d0bf81a7 SHA-256: a351d23b753cdf5ad82f8047a9e42de3dd51f365c15368fc69120638a3747ff6

80 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample 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 embedded macro code is heavily obfuscated but appears to be constructing and executing a command that includes a long, complex string, likely a payload or a URL to download one. The presence of the Auto_Open entry and the obfuscated macro code strongly indicate a malicious intent to deliver an additional stage.

Heuristics 2

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.
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` `71625bb4f9af346411314f55d5a953c644bca6f192657d504d127f4ad3ac51ba`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	15664 bytes

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