Malicious RTF — malware analysis report

Static analysis result for SHA-256 d38eb1926b1fede7…

MALICIOUS

RTF

16.6 KB First seen: 2023-02-23
MD5: e9417c69cae2642f334d6666a4fce376 SHA-1: c1829ebb53ae2cd39dc2fc7dd7edfc70ed1b8326 SHA-256: d38eb1926b1fede7be353b6eb2f0655fb795129f790a849e3454ba22cc7755b1
180 Risk Score

Malware Insights

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

The RTF file contains OLE object data and specifically triggers the Equation Editor vulnerability (CVE-2017-11882). This indicates the file is designed to exploit this known vulnerability for initial execution. The presence of ".objdata" and ".objupdate" directives further confirms the malicious intent to activate embedded objects. No specific family could be identified, but the exploit method is clear.

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_off00001ec4.bin
f25ed7dbfebd53532ed5dc0ae5ff4753cbb6bf152563192a30611782c3c81c23
rtf-objdata-decoded RTF \objdata at offset 0x1EC4 1949 bytes