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

Static analysis result for SHA-256 c25c516c7883db97…

MALICIOUS

Office (OLE) / .XLS

229.0 KB Created: 2020-09-20 21:17:44
MD5: c5a36feaaec87e764066e647555e1291 SHA-1: d300c3774476f17b026c6ac099d08f8c0dcb7aed SHA-256: c25c516c7883db97ae23bb6469ecbed03f450141ddb39112866d93813a05e67f
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that executes dangerous functions. The extracted XLM macro explicitly constructs and executes a PowerShell command. This command downloads a file named 'o.exe' from the URL https://tinyurl.com/y846dd2m to the user's appdata directory and then executes it.

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
73c2122b9dbaf96695ba47473594741cbcbf7578ef496cacbb37cfde27558d29
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1384 bytes