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

Static analysis result for SHA-256 c1fc12d87d967a94…

MALICIOUS

Office (OLE) / .XLSX

149.0 KB Created: 2020-05-03 13:28:15 Authoring application: Microsoft Excel
MD5: 8420c2efa7f313594b8ef03b497e903f SHA-1: 305677afff7ff8489f4184950142078226d499f4 SHA-256: c1fc12d87d967a945ce40e0a8f72b922a98925a8ac390823aef988c6ac9879a0
300 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment T1059.003 Windows Command Shell T1105 Ingress Tool Transfer

The file contains Excel 4.0 macros, specifically an Auto_Open macro, which is a critical indicator of malicious intent. The presence of `ShellExecute` and `certutil` API calls suggests the macro is designed to download and execute additional malicious content. The ClamAV detection further supports its classification as a downloader trojan. The VBA macros also contain functions like `ReCalulateTable` which calls `Worksheets(FirstRow).SaveAs SecondRow, 42`, indicating potential file manipulation or execution.

Heuristics 7

  • 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.
  • ClamAV: Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Trojan-bf70f023603538ee-bf70f023603538ee-9950269-0
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Reference to certutil (download/decode) high SC_STR_CERTUTIL
    Reference to certutil (download/decode)
  • 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.
  • VBA macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
25413e0acdae9f16af7ede42b24498708ac82c3bec5d57cd55b22fa90cab2af4		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6039 bytes
macros.bas
0ed41587673da3b0ed61d44590cd1adba2a381bf2d97762270f7adc025c7f34f		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 3019 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.