RTF malware analysis — malicious · 61b5949d0e0a0f83

MALICIOUS

RTF

9.1 KB First seen: 2019-04-18

MD5: 4a38d332297395e365979896a3fc4563 SHA-1: 2be97740b0863471f03fb0e10e09209ab48afc91 SHA-256: 61b5949d0e0a0f83a0e578071bd78bc946d8ee01d8977bd2790202a1209ddbd2

300 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object with a CLSID indicative of Microsoft Equation Editor. Heuristics strongly suggest exploitation of CVE-2017-11882, which allows for arbitrary code execution when the embedded object is activated. This is a common technique for delivering malicious payloads via spearphishing attachments.

Heuristics 7

Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR

Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
Equation Editor Ole10Native payload — CVE-2017-11882 likely critical CVE likely CVE_2017_11882_EQUATION_OLE10NATIVE

RTF decodes to an activated Microsoft Equation 3.0 OLE storage whose payload is a high-entropy Ole10Native stream rather than normal Equation Native/MTEF data. This is a weaponized Equation Editor RCE delivery shape consistent with CVE-2017-11882/CVE-2018-0802.
Ole10Native stream in RTF OLE object high CVE related RTF_OLE10NATIVE_STREAM

RTF contains an embedded OLE object with an Ole10Native stream. This is a strong payload-container signal and is related to Word/OLE exploit delivery, but it is not specific enough on its own to assign a CVE.
ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
\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 1 \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.

Filename	Kind	Source	Size
`objdata_00_off0000003b.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x3B	4648 bytes
SHA-256: `6bf3b12242a3b2001ac1b6cbf00639ef5039b24deb1b9f0f5a6c15918b368ec7`

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