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

Static analysis result for SHA-256 28cc94fb40f206ec…

MALICIOUS

Office (OLE) / .XLSX

59.5 KB Created: 2015-06-05 18:17:20 Authoring application: Microsoft Excel
MD5: eb2bed8bb4507618e604c64bc8759293 SHA-1: a6a9214ae08a5e1051302cf939d6cd08406f9ee9 SHA-256: 28cc94fb40f206ecd64d4fad4b6955ec81ffe52065b7249d0bf324e766b4d413
160 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample contains Excel 4.0 macros, specifically an Auto_Open function, which is a critical finding. The macro uses the REGISTER function with a URL constructed from concatenated strings, indicating it attempts to download a second-stage payload from 'http://writtendeer.com/cosmo/solomon.php'. The presence of the 'SE_ENABLE_LURE' heuristic suggests the document likely prompts the user to enable macros. The EXEC function is also present, further supporting the execution of downloaded content.

Heuristics 4

  • 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.
  • 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
d2a1f933717de73425d1c8c42b15a2a39422596b28f0deddd18d06db73e15326
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2301 bytes