Malicious Office (OLE) / .XLSX — malware analysis report

Static analysis result for SHA-256 34683184956ac22b…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-25 10:25:41 Authoring application: Microsoft Excel First seen: 2023-03-30
MD5: 623320e71aeb5208d72fa2e0bd074f21 SHA-1: edb0a1f429c923abb7eb9c7e254c74fcd31f2585 SHA-256: 34683184956ac22bf8dbc9d3b8cc77961029956ad83b94b10c7d25fc1382dcd8
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1566.001 Spearphishing Attachment

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding indicating automatic execution. The heuristics also flag the use of dangerous formula APIs within the XLM macro, suggesting an intent to perform malicious actions. The presence of an Auto_Open entry strongly suggests this file is intended to be delivered as an attachment, likely via spearphishing, to execute its payload upon opening.

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.

FilenameKindSourceSize
xlm_macros.txt
1247ce9aa6453b78844f9ed02d40d09135246892cefe303c2e37892661c37f49		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6355 bytes

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