Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 53f9cb3e338067bf…

MALICIOUS

RTF / .DOC

4.8 KB First seen: 2021-10-23
MD5: 10c2bab7a44816e0c5c54cb8d21ef46d SHA-1: a6560322c706cbed52cb3a32f6a02ec6d399a12c SHA-256: 53f9cb3e338067bfbd0683a69f29ab8848d9f2494750d6d36683871523b01625
120 Risk Score

Malware Insights

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

The file is an RTF document containing embedded OLE object data, specifically targeting the Equation Editor vulnerability. The presence of ".objupdate" indicates that the embedded object is designed to be activated automatically upon opening, leading to code execution. This is a common delivery mechanism for exploiting known vulnerabilities to download and execute further stages.

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_off000000b4.bin
d6db0b37fd33b176d7a6bf64e096879de762271ffc2c27a578689564d7c69619
rtf-objdata-decoded RTF \objdata at offset 0xB4 2128 bytes