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

Static analysis result for SHA-256 1af1389d365a5178…

MALICIOUS

Office (OOXML) / .XLSX

278.8 KB Created: 2000-11-15 22:33:24 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-07-11
MD5: 6cab85f951ccd2056673c96e0290e04f SHA-1: f872386f17ac8186a1257e7321faa63b7a3ac88c SHA-256: 1af1389d365a517879d7acccb5c0f52881062aa41d05a4d79fb51a25f0dc701f
422 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample is a macro-enabled Excel document containing an Auto_Open VBA macro that utilizes the Shell() function. This macro is designed to download and execute a second-stage payload from an embedded URL. The presence of obfuscated shell commands and the ClamAV detection as 'Doc.Dropper.Agent-5745061-0' strongly indicate a dropper functionality.

Heuristics 11

  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Obfuscated VBA Shell command with URL critical OLE_VBA_OBFUSCATED_SHELL_URL
    VBA macro invokes Shell with command text assembled through decoder or string-manipulation functions and includes a URL. This is a high-confidence downloader/dropper pattern, stronger than Shell or URL evidence on their own.
  • ClamAV: Doc.Dropper.Agent-5745061-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Dropper.Agent-5745061-0
  • 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.
  • Auto_Open macro high OLE_VBA_AUTO
    Auto_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Remote image (web beacon / tracking pixel) medium OOXML_IMAGE_BEACON
    Document references an external image URL — loads automatically on open, revealing IP address and timestamp to the server (used for phishing tracking and NTLM hash theft on corporate networks)
  • External relationship medium OOXML_EXTERNAL_REL
    External target in xl/drawings/_rels/drawing1.xml.rels: https://eu.knowbe4.com/usb_campaigns/report/SzJGNVRWaGxRV1kyYVRSSGVEbFViRXAzYnpSQ1RrSk9PVFYwV1V0VmEwVkllbklyZGtWaVdXTTFa
  • 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://Motobit.cz
    • https://eu.knowbe4.com/usb_campaigns/report/WVhGc1dWaHdRemRvUVc1cUswOTZSWGdyYm5SbmNpOUtWRXRIUjNGd09GSXJlbTFxTUc1RVZFdE9WMGxyUkdWbU9ITXljbWx0ZWtGTFRVOHlRVU5qYms1bmRFcElWbWh1Wm5SaFRtTmliekJGZEVwTU9FRTlQUzB0U0VWaE4wTXJaWEJ3T1RWUFFVVjJjMVZIVEV4RlVUMDktLWJjMTQ0OWNmOWM4OTZiZjE1ZGRjNmNiNGM3NGQ5YTdhZjM2YWMyMTI=
    • https://eu.knowbe4.com/usb_campaigns/report/SzJGNVRWaGxRV1kyYVRSSGVEbFViRXAzYnpSQ1RrSk9PVFYwV1V0VmEwVkllbklyZGtWaVdXTTFaRVZuWWsxR2JsVlNWMWxZWm1kSFNGVkZiMkZCV2tsamREVjRVa2hGY2pkT1Z6SXhNVU5HZGxweksxRTlQUzB0YjBwcWNsbHpXV3B6TkRsdFVqQm5MMlZ0VmtkMFp6MDktLTcyZDFjYTlhMTkyNWE5ZjkyYzA3OGRiOWJjNjYzNzhiODUxODBj
    • https://eu.knowbe4.com/usb_campaigns/report/SzJGNVRWaGxRV1kyYVRSSGVEbFViRXAzYnpSQ1RrSk9PVFYwV1V0VmEwVkllbklyZGtWaVdXTTFa
    • https://eu.knowbe4.com/usb_campaigns/report/SzJGNVRWaGxRV1kyYVRSSGVEbFViRXAzYnpSQ1RrSk9PVFYwV1V0VmEwVkllbklyZGtWaVdXTTFaRVZuWWsxR2JsVlNWMWxZWm1kSFNGVkZiMkZCV2tsamREVjRVa2hGY2pkT1Z6SXhNVU5HZGxweksxRTlQ

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
d6838ed4a8cb5a9cd7fb923c36fec68b8797bde19a3aad50a2bd226e71ff16f8		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 8942 bytes
vbaProject_00.bin
c2aa7021c472bae214be9671018541d3e4bbc1ec98a9c304cb408601cb32c07b		 vba-project OOXML VBA project: xl/vbaProject.bin 31232 bytes
Detection
ClamAV: Doc.Dropper.Agent-5745061-0
Obfuscation or payload: unlikely

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