RTF malware analysis — malicious · e66ace9814f90c14

MALICIOUS

RTF

367.7 KB First seen: 2018-08-26

MD5: f11ad662af74770754f08960f0d2012d SHA-1: c69233cf41b47041f537537ab57614087aa4845d SHA-256: e66ace9814f90c1456b6d34e853706874e364b80ef85de08a5d5beeea17de54d

360 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment

The sample is an RTF document that contains a critical heuristic indicating exploitation of CVE-2017-11882 via the Equation Editor. This exploit is known to download and execute a second-stage payload, likely leading to further system compromise. The presence of OLE object data and references to mshta.exe further support this attack vector.

Heuristics 8

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
Reference to mshta.exe high SC_STR_MSHTA

Reference to mshta.exe
Automatically linked OLE object high RTF_OBJAUTLINK

RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
\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

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off0000003f.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x3F	118439 bytes
SHA-256: `ec11c34d1a9334de598e47ec86e4e6f13d01ba1fd0c6ffaa8a6c399e7046fb15`

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