Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 23c8af917aca19ca…

MALICIOUS

RTF / .DOC

3.5 KB
MD5: 9b1bfd5f5389758f5bca2a2331f2a1ca SHA-1: c70506f407acf57371ad93c20b1127fe42466e34 SHA-256: 23c8af917aca19ca6ec3ea6ad86600ea6dab859c910e03ad9f9f471bc2267a5d
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains embedded OLE objects, specifically triggering the Equation Editor vulnerability (CVE-2017-11882). The presence of ".objdata" and ".objupdate" sections, along with the "eqUation.3" ProgID, strongly indicates exploitation of this known Microsoft Office vulnerability. This technique is commonly used to deliver 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 2 \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_off00000104.bin
f32e29d2f9dfe0963f49e71b8a7117ee1c1a808a2c49705ca997f39fce888382
rtf-objdata-decoded RTF \objdata at offset 0x104 1543 bytes