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

Static analysis result for SHA-256 74cdd5e924e15e45…

MALICIOUS

Office (OLE) / .XLS

392.5 KB Created: 2020-09-20 21:17:44
MD5: c32cd36c4ac0d06d321422080da164c8 SHA-1: ded311853adf3cfc018be4f310bbfba6fcbd0357 SHA-256: 74cdd5e924e15e451b3201884c8e647061d5d1e3a7e6cb88fccbb7f26878f1e2
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, specifically using dangerous functions like RUN. The extracted macro script reveals it constructs a PowerShell command to download a file from 'https://cutt.ly/mjfU5y0' and save it as 'sm.exe'. It then attempts to execute this downloaded payload, likely establishing persistence.

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
7de3969434353343e13eb9b2a0b57bc81034379709bc44b525d3f31f13bea8af
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1347 bytes