Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 7864259271e30938…

MALICIOUS

RTF / .DOC

27.2 KB First seen: 2021-09-17
MD5: 80e2fccb0933da6f12b59c3346e019e4 SHA-1: ffe4eb6e8566813fead3c33f0ab501d471a09837 SHA-256: 7864259271e3093868fee8cdd41914d8dff505b78f44821bc619e9614340afec
120 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF document containing embedded OLE objects and triggering heuristics for the Equation Editor vulnerability. The ".objupdate" directive forces the activation of these objects, which is a common method for exploiting this vulnerability to achieve code execution. The presence of these indicators strongly suggests the document is designed to exploit this known vulnerability, likely as a delivery mechanism for further malicious activity.

Heuristics 3

  • 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 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000015ac.bin
98e9c2344c778792a49d4a8066736b2130e8ea0f9f3e01923819006af95c3350
rtf-objdata-decoded RTF \objdata at offset 0x15AC 2065 bytes