Malicious RTF — malware analysis report

Static analysis result for SHA-256 aea27be79ec5469a…

MALICIOUS

RTF

87.9 KB First seen: 2019-05-16
MD5: 847f5faa805fa9814ec99cc5bcad50ef SHA-1: 56a9b9fc663b45de10f593eda3b95c68f945c9b3 SHA-256: aea27be79ec5469aa1c3813d162ac468a00ddc127652092fdd6c01b5ad2ffcd1
200 Risk Score

Malware Insights

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

The RTF file contains evidence of the CVE-2017-11882 vulnerability in Microsoft Equation Editor, indicated by multiple high and critical heuristic firings. This exploit typically allows for the execution of arbitrary code, which is often used to download and run a second-stage payload. No document body text or scripts were extracted, but the exploit itself is sufficient to infer the attack pattern.

Heuristics 5

  • Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • 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_off0000b27c.bin rtf-objdata-decoded RTF \objdata at offset 0xB27C 1642 bytes
SHA-256: 51cf386b40b404055c8a32cf186fb171584f2a959f164973fafb010c7632189f

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