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

Static analysis result for SHA-256 6275d4f129dd2298…

MALICIOUS

Office (OLE) / .XLS

268.0 KB Created: 2021-02-06 22:23:31 Authoring application: Microsoft Excel
MD5: 9185b44e8609ed1f020719ee053dc180 SHA-1: ad6e70b586b186762f54a5aa114098e0db625af9 SHA-256: 6275d4f129dd2298ad43c1354d61f33880a032752300824a4fed06528d2c6349
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The critical heuristics indicate the presence of Excel 4.0 macros with dangerous formula APIs, specifically triggering an Auto_Open event. The extracted macro code constructs and executes a PowerShell command to download a file named 'sv.exe' from the URL 'https://tinyurl.com/y3njysh9' and save it to the user's AppData directory, likely as a second-stage payload. The use of Auto_Open suggests this file was likely delivered as a spearphishing attachment.

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
f844d8aa8ac402b50839a03dc3fca6b6d673ad660a77576daa529d726e84d5b4
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1242 bytes