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

Static analysis result for SHA-256 1de3f0aa5c1d481b…

MALICIOUS

Office (OLE) / .XLSX

36.5 KB Created: 2020-11-27 11:44:23 Authoring application: Microsoft Excel
MD5: 70146d221a55ad6835a8ebff4b71a935 SHA-1: 885c35756ab84b723c309370b262dcbfc8e88e39 SHA-256: 1de3f0aa5c1d481b74ea58b656e547c167b7d42a45cf60f155f9929178c3048c
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1059.001 PowerShell

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code upon opening the document. The critical heuristic firings indicate the presence of dangerous formula APIs within the XLM macro, suggesting it's designed to run commands. While no specific URLs or hashes were extracted, the presence of the Auto_Open macro strongly implies a downloader or initial execution stage for further malicious activity.

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
ccdc242436dff7db293803f165f1090dce9397173a2022dad19e502db64df031
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6956 bytes