Malicious RTF — malware analysis report

Static analysis result for SHA-256 f72bc34b4c535892…

MALICIOUS

RTF

12.7 KB First seen: 2023-02-08
MD5: 2bd67a6d299cf98ad1c51e59dc70098f SHA-1: 8d228742f2ad298c49e29e1bac0aa6951e12e401 SHA-256: f72bc34b4c53589243bc1effab31c2f655c92f21faadebcc7d2d83196a1bad1a
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The heuristics indicate that the ` tfobjdata` and ` tfobjemb` tags are used to embed and activate this object, which is a known method for exploiting this vulnerability. The `CVE_2017_11882_ACTIVATION_RELATED` heuristic confirms the exploit attempt.

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_off00001c44.bin
6b3e520c3e260cf8a99878c77c77845f1c68b5583b3b301818432ae8f76537ee
rtf-objdata-decoded RTF \objdata at offset 0x1C44 1339 bytes