RTF / .DOC malware analysis — malicious · 40fceea462792a9c

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-15

MD5: 68bb54c35a5f82aba426df726fa24533 SHA-1: fa957f54b5a98ce0461483362e5d69029b013204 SHA-256: 40fceea462792a9c1117fa6a794987d6b4d6f273ebef3bf421d61e56c1170305

180 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The critical heuristic firing RTF_EQUATION_EDITOR, along with CVE_2017_11882_ACTIVATION_RELATED, strongly indicates exploitation of CVE-2017-11882. The RTF document contains embedded OLE objects, and the ".\objupdate" directive forces their activation. The decoded object data appears to contain obfuscated VBA code, likely intended to download and execute 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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00001347.bin` `877a288ac2d05ac25341bc15eb5b9b696da33b6861145472f32babe2662e69a3`	rtf-objdata-decoded	RTF \objdata at offset 0x1347	25544 bytes
`objdata_01_off000194e2.bin` `689965aaaf88dfda2c46136e8ee45ccbdf5d380abcba88d5f9ff529d3c59ced2`	rtf-objdata-decoded	RTF \objdata at offset 0x194E2	463381 bytes

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