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

Static analysis result for SHA-256 a1ddbc2615efc0e5…

MALICIOUS

Office (OLE) / .XLS

71.0 KB Created: 2020-05-20 08:20:55 Authoring application: Microsoft Excel
MD5: 2887b34fb78b613da8cc8a6b47094d1b SHA-1: 45de728104901b38cf4236fa9a106f45bf746e68 SHA-256: a1ddbc2615efc0e594b609aed7e369b6fec8c6897d87c8d22c91a9f65c41ef6e
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File

The file contains Excel 4.0 (XLM) macros, specifically an Auto_Open macro, which is a critical indicator of malicious intent. The macro utilizes dangerous formula APIs, including the RUN function, to execute arbitrary commands. The obfuscated document body and the presence of an Auto_Open macro strongly suggest that this file is designed to download and execute a second-stage payload from the reconstructed URL: http://os.mediarncbx.com/DGVCqBLjyrbJMgJNbl. The use of XLM macros points to a downloader or initial access mechanism.

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
8802d9ccc31363571bb5c72a8cabde8ec36203c7b23b87b6e58cac1a5b57e4b5
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 38817 bytes