Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 bf8a704049307e97…

MALICIOUS

RTF / .DOC

66.2 KB
MD5: a5f6bf3990ea85086c982f650f63860f SHA-1: 069c1d4de70f8983bcd8777e39c355571be413c1 SHA-256: bf8a704049307e97a631728a60291fb78f9ba85ac74f85e2c7d5ae7c5e60af57
180 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The presence of ".objdata" and ".objupdate" sections, along with the specific Equation Editor ProgID, strongly indicates exploitation of this known flaw. This technique is commonly used to deliver a secondary 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_off00000cae.bin
2bcee56d43399e5966b519b77433b5335ed50ce8183e67cddc82fb8f41ceab71
rtf-objdata-decoded RTF \objdata at offset 0xCAE 1681 bytes