Malicious RTF — malware analysis report

Static analysis result for SHA-256 bd97a7bc86a8a39d…

MALICIOUS

RTF

11.8 KB First seen: 2023-03-10
MD5: 136b8caad2005796261daac7c638ba53 SHA-1: 5265afda7e998aad2fe2625e88ccddc191662e77 SHA-256: bd97a7bc86a8a39dd3e916a84826d90b3cac62c86e6bbf57c10c1937942f2edc
180 Risk Score

Malware Insights

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

The RTF document contains an OLE object specifically crafted to exploit the Equation Editor vulnerability (CVE-2017-11882). The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates this exploit. The ` tfobjdata` and ` tfobjemb` sections confirm the embedding of an OLE object, and ` tfobjupdate` forces its activation, leading to the execution of the malicious payload.

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.
  • \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
  • 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_off00000b47.bin
e8576308951996379d766afba312f4a876faac1418289cada3602e184b64b051		 rtf-objdata-decoded RTF \objdata at offset 0xB47 1736 bytes

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