Malicious RTF — malware analysis report

Static analysis result for SHA-256 866aae36968c3a3c…

MALICIOUS

RTF

3.4 KB First seen: 2020-09-07
MD5: 2165e16c6e6d5f95fdb9628c7b79fad7 SHA-1: 974aae276216813646cef698c96ee7b7fb7714da SHA-256: 866aae36968c3a3c720b971bf944d39052aa3e04ad1c4aaf60fdcb74e13435bd
200 Risk Score

Malware Insights

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

The RTF file contains embedded OLE object data, specifically related to Microsoft Equation Editor. Heuristics indicate the exploitation of CVE-2017-11882, a known vulnerability that allows for arbitrary code execution when Equation Editor is activated. The presence of `eQuATIoN.3` as the ProgID strongly suggests this exploit.

Heuristics 5

  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000047.bin rtf-objdata-decoded RTF \objdata at offset 0x47 1617 bytes
SHA-256: 468c1c5effc1a84df3e6742231e133b901037c7722ef584c1eabf975bb759adb

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