Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 4bb6d08dad879c7e…

MALICIOUS

Office (OOXML) / .XLSM

102.2 KB Created: 2021-08-19 14:03:52 UTC Authoring application: Microsoft Excel 15.0300
MD5: c23ce4292b1f9362d12198167849bb80 SHA-1: 78665b05a2b48809edd743b658cf25d731d5f5e6 SHA-256: 4bb6d08dad879c7e0098024d645c92c198484e1d7703019fa0db7ead6f867bfd
382 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1059.003 Windows Command Shell

The sample is an XLSM file containing a Workbook_Open macro that executes a command using cmd.exe. This command uses certutil.exe to download a batch file from http://3.112.243.28/net/Nhmrwsew.bat and then executes the downloaded file. The ClamAV detection of 'Xls.Dropper.EPPlus-9802867-2' further confirms its malicious nature as a dropper.

Heuristics 9

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • LOLBin reference in VBA critical OLE_VBA_LOLBIN
    LOLBin reference in VBA
  • ClamAV: Xls.Dropper.EPPlus-9802867-2 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.EPPlus-9802867-2
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • cmd.exe reference in VBA high OLE_VBA_CMD
    cmd.exe reference in VBA
  • Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — VBA macros present
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://3.112.243.28/net/Nhmrwsew.bat

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
d4ceb2d9327837bc4a55aa072bd1334df155ebd73193b0f2ffc67523e380e65c
vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1091 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved macro source contains an auto-exec entry point and execution/download terms.
vbaProject_00.bin
f336a46fd4981cae3ef2894ed4e719e9d4d38e855a37cce09176c11b844b798b
vba-project OOXML VBA project: xl/vbaProject.bin 5632 bytes
Detection
ClamAV: Xls.Dropper.EPPlus-9802867-2
Obfuscation or payload: unlikely