RTF / .DOC malware analysis — malicious · d26ace7878a5e74f

MALICIOUS

RTF / .DOC

2.09 MB

MD5: 9aa277d2181e6bf78fea180c798124cd SHA-1: f13c8aabaecc291e8273457ee4498c3b3d2cb39b SHA-256: d26ace7878a5e74f14de4641245be92271c19297cfd252f2956ee7f7329556d8

180 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment T1204.002 User Execution: Malicious File T1204.001 name: User Execution: Malicious File T1204.001 User Execution: Malicious File

The sample is an RTF document containing embedded OLE objects and a split hex Equation Editor ProgID. The presence of CVE-2017-11882 activation triggers and the objupdate force activation flag indicates a high probability of the own vulnerability exploitation for initial access. No scripts or document body text were extracted, but the structural evidence strongly supports a CVE-2017-11882 based attack pattern.

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` `435d32daea5e25bbf17ed7475ef1dab4eb05cbb047337af758882163efd17e0f`	rtf-objdata-decoded	RTF \objdata at offset 0x1202	27315 bytes
`objdata_01_off0001cf73.bin` `2f05c0110283d6d66817dd760d3b8c77e60c29eaf269a6c8a7c9412afdda699d`	rtf-objdata-decoded	RTF \objdata at offset 0x1CF73	362865 bytes

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