Malicious RTF — malware analysis report

Static analysis result for SHA-256 495d5bef751f7e60…

MALICIOUS

RTF

12.4 KB First seen: 2022-08-01
MD5: b1d12e6e02b934a0f8ef39d29b45ab74 SHA-1: b4ab1e49b4efbe432f2792e96f71ce18ee6ee064 SHA-256: 495d5bef751f7e60f52180c05a69445d16174b4eef2711e2dfe7e716d50a3196
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1559 Component Object Model Hijacking T1059.005 Visual Basic

The RTF document contains an embedded OLE object that triggers CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The heuristic firings indicate that the object is obfuscated and designed to be activated via \objupdate, strongly suggesting an attempt to execute arbitrary code. The document body contains a lure to 'enable editing', further supporting the malicious intent.

Heuristics 6

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • \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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001d2d.bin
44b89f70ffca13cb5bdb6042d56f26cfb28b90afbb9d612e513fd85865a3a9d8		 rtf-objdata-decoded RTF \objdata at offset 0x1D2D 1592 bytes

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