Malicious RTF — malware analysis report

Static analysis result for SHA-256 b68543e8270c37e0…

MALICIOUS

RTF

1.00 MB First seen: 2019-01-12
MD5: cd1459f77a43aec0835771ae286a52f6 SHA-1: a5f3c33ba19b24a39407e6bf5c1b2acb08250142 SHA-256: b68543e8270c37e09011d4554a0e326889f2da0cced4b2d1247cbbe99ce45494
240 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data and triggers the \objupdate directive, indicating an attempt to activate embedded content. Critical heuristics identify the CVE-2017-11882 vulnerability, commonly exploited via the Equation Editor, and ClamAV confirms this detection. The large amount of hex-encoded data within the OLE object suggests it is used to hide a malicious payload, likely delivered through exploitation of this CVE.

Heuristics 6

  • 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: Doc.Exploit.CVE_2017_11882-6934206-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.CVE_2017_11882-6934206-0
  • \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 ~1043KB 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001528.bin rtf-objdata-decoded RTF \objdata at offset 0x1528 4142 bytes
SHA-256: 72fd224f61c2eb1bdcf59665f1ba216560b89651d927ab9d04f4f9b6d6e8583b

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