Malicious RTF — malware analysis report

Static analysis result for SHA-256 46e413bc26689129…

MALICIOUS

RTF

13.3 KB First seen: 2023-03-04
MD5: 0abfe119e17fbffb3bd81577d97de405 SHA-1: e52360060779acc30333a739d347caaea733a0f3 SHA-256: 46e413bc266891295b80f03d7fc987bde2d18f979a0709942d7d799ef787ba9b
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious File T1566.001 Spearphishing Attachment

The RTF file contains an OLE object that exploits CVE-2017-11882 via Microsoft Equation Editor. This vulnerability is commonly used to execute arbitrary code, likely to download and run a second-stage payload. The presence of RTF_OBJDATA, RTF_OBJAUTLINK, RTF_EQUATION_EDITOR, and RTF_OBJUPDATE heuristics strongly indicates this exploit.

Heuristics 5

  • 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.
  • Split hex Equation Editor ProgID + OLE object critical 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.
  • 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_off000016c6.bin
09a78680ed791ea6f7b2e1097688f70452f20d4caa1c8dc294bf698d36e61355		 rtf-objdata-decoded RTF \objdata at offset 0x16C6 1671 bytes

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