Malicious RTF — malware analysis report

Static analysis result for SHA-256 89f834c17348a6bb…

MALICIOUS

RTF

11.6 KB First seen: 2023-02-09
MD5: a604cc88f63b055d08ae741f1183951c SHA-1: 4eb8f6e4c572b5968aacea440724cea0e8db8025 SHA-256: 89f834c17348a6bbd04febb78911de13bfeb6c2d6ec084a1b4f2c72718308f3b
180 Risk Score

Malware Insights

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

The RTF document contains a critical heuristic firing for Equation Editor exploitation (CVE-2017-11882). This indicates the file is designed to leverage this known vulnerability. The presence of OLE object data and objupdate directives further confirms the intent to activate and execute embedded malicious content, likely leading to a second-stage 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_off00000dc6.bin
f3f579166033cf9eaa11299b95342d9db2a32706946f6546aca3f5984808463a
rtf-objdata-decoded RTF \objdata at offset 0xDC6 1976 bytes