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

Static analysis result for SHA-256 f05874d2a90c7863…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:39:26 Authoring application: Microsoft Excel
MD5: 043e48f32479a3abd85a5139953f693c SHA-1: b4d4c0d9a0557450222ec02fdd35b62b1109f59f SHA-256: f05874d2a90c7863f001417a4788096f2631c7698f1beb14f0ab9ca0a803165e
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The file is an Excel spreadsheet containing Excel 4.0 (XLM) macros. Critical heuristics indicate the presence of an Auto_Open macro, which is a common technique for executing malicious code upon opening the document. The macro sheet contains a reference to 'Auto_Open' and uses dangerous functions like 'RUN=0', strongly suggesting it's designed to download and execute a secondary payload. No specific URLs or hashes were extracted, but the technique itself is highly indicative of a downloader or initial access stage.

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
a67321f1ac5560251e57c22d73873f84f3a737f33b3527a1cbbf846b2961bb12
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6488 bytes