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

Static analysis result for SHA-256 d556b7e0820a135e…

MALICIOUS

Office (OLE) / .XLS

36.0 KB Created: 2020-11-25 10:29:19 Authoring application: Microsoft Excel First seen: 2022-04-23
MD5: 87085753ac1e1b374844a3dddf59e59c SHA-1: bf87256d0aa454fca66a6995c4a0a95b799a2d92 SHA-256: d556b7e0820a135edcd80ca58d4854a46c5f0d309f26d2d4d8c5b5a8686c6286
140 Risk Score

Malware Insights

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

The sample is an Excel 4.0 macro-enabled spreadsheet. Critical heuristics indicate the presence of an Auto_Open macro, which is a known technique for executing malicious code upon opening the document. The macro is likely designed to download and execute a second-stage payload, although the specific URL or payload is not directly visible in the provided evidence. The use of XLM macros and the Auto_Open function points to a common delivery mechanism for malware.

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
f05d22ce6b07590cfc3dc00c013d8cd8b1245728943020309920c529fe81d724
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6658 bytes