Office (OLE) / .XLSX malware analysis — malicious · f73d2dac27db2112

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:43:47 Authoring application: Microsoft Excel

MD5: e779fe6fb5b1e43a20ddee80288eb4f4 SHA-1: 338644de8228c8a0f6d6e892fffda6eeaf37b3ef SHA-256: f73d2dac27db211208a56ffa95518889802b9c105c3c8487f6c25ee41b4b64c5

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample contains Excel 4.0 macro sheets with an Auto_Open defined name, indicating that malicious code will execute automatically when the workbook is opened. The heuristics indicate the use of dangerous formula APIs, specifically the RUN function, which is commonly used to download and execute arbitrary code. No specific family could be identified, but the technique suggests a downloader or initial access vector.

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` `bbe17c0ef071cce8360f82f4e2726fc238bf0fd1c1362f013a3853b521e23511`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6708 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.