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

Static analysis result for SHA-256 01af3b5c1e2ed682…

MALICIOUS

Office (OLE) / .XLS

76.5 KB Created: 2020-12-07 14:38:21
MD5: 91baa6aad9201c0ccf3553a5b49eb967 SHA-1: 9c182826d5dc041970f31a8d584580f870c3996c SHA-256: 01af3b5c1e2ed68272f542233aece70269a9e977815347a4b9c86bb2d97c086e
100 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.002 Spearphishing with Malicious Attachment

The file contains both VBA and Excel 4.0 (XLM) macros, with a critical heuristic indicating that VBA ActiveX events trigger worksheet-decoded XLM formulas. The VBA macro attempts to execute a dynamically constructed string via MsgBox, which likely leads to the execution of the XLM macro. The XLM macro appears to be obfuscated and contains numerous numeric values, suggesting it's designed to download and execute a secondary payload.

Heuristics 3

  • VBA ActiveX event runs worksheet-decoded XLM formulas critical OLE_VBA_ACTIVEX_XLM_CELL_STAGER
    VBA code attached to an ActiveX/UserForm event reconstructs formula text from worksheet constants using Split/Replace/Mid or character shifting, then executes it through ExecuteExcel4Macro or Run. This is a high-confidence malware stager that hides XLM formula execution in sheet cells; it is not a document-parser CVE.
  • 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.
  • VBA macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
e4855c55bf3129eb726f9f27bef15b425266722ce8751c8c70b3578c5f2ecc52
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 50902 bytes
macros.bas
4a71708e274041e7f4b61d5df83028298bc9e092e428acb01e64e07f1b484a5f
vba-macro oletools.olevba.extract_macros (decoded VBA source) 1832 bytes