RTF / .DOC malware analysis — malicious · c39d09f8edcdf24b

MALICIOUS

RTF / .DOC

2.21 MB

MD5: 31ac9aaf052063476d9a0bfc1f8adb55 SHA-1: 230115ea3528bc944c081fe968df8d0ae7432033 SHA-256: c39d09f8edcdf24b9a7c3c6175429affdc6559334c94e50aebd6e21390fc9d6f

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 `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics indicates that the file is designed to exploit this known vulnerability. The `RTF_OBJUPDATE` heuristic suggests that the embedded object is forced to activate, leading to arbitrary code execution. No specific family could be identified, but the attack pattern is consistent with exploiting a known Microsoft Office vulnerability for initial access.

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_off00001202.bin` `bdc60af73994ded9662d15aa9542427b9ab341032bc1bac936b1fda16985d84e`	rtf-objdata-decoded	RTF \objdata at offset 0x1202	27140 bytes
`objdata_01_off0001c9c9.bin` `1a9daf7f5259077ae9a7fba5e35fb7f5d70b6d43574b5a4ed8dc4e9c9ad184d1`	rtf-objdata-decoded	RTF \objdata at offset 0x1C9C9	475057 bytes

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