RTF malware analysis — malicious · f5c35a43c5379d70

MALICIOUS

RTF

15.6 KB First seen: 2019-05-16

MD5: 8269e1b36d5bec599b73509fcd767de2 SHA-1: d884a7fd2cc71f66022cb5598ba6c1473183aaf5 SHA-256: f5c35a43c5379d705d3f1575a3859934261a87f27b669cc3ddbf6e601ba00abc

300 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF document containing an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). This exploit allows for arbitrary code execution, which is a critical finding. The presence of the Equation Editor CLSID and the Ole10Native stream strongly indicate exploitation of this specific vulnerability. The ClamAV detection further confirms its malicious nature as Rtf.Exploit.CVE_2017_11882-6584355-1.

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_off00001a10.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x1A10	4669 bytes
SHA-256: `002ca38a534ed6ae20d791cd239950f275b1a18dfe65fb94dc8a51bd1030423f`

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