Office (OLE) / .XLSX malware analysis — malicious · 76996244af1dea2c

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-27 11:40:08 Authoring application: Microsoft Excel

MD5: 1b0d3f00a53c6e1d0ae1c250e0763d7f SHA-1: b7bc7ee727acab9469f758b159f2e4f597829b13 SHA-256: 76996244af1dea2c1fa5e956add1804b0dfe66b63a73aa98774b8e38e5eca63f

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open defined name, which is a known method for executing malicious code upon opening the workbook. The macro sheet contains a reference to a dangerous formula API, suggesting it's designed to run commands. The document body contains obfuscated text, further supporting a malicious intent to hide its functionality.

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` `d04b82f916243b32001f10b034bb9ad46579891de25bec0b3cd97f6f19550309`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6837 bytes

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