Malicious RTF — malware analysis report

Static analysis result for SHA-256 8de820d776209228…

MALICIOUS

RTF

9.9 KB First seen: 2018-07-27
MD5: 890633d9f586a1b2cecc07e3e650d360 SHA-1: 66db6b85fba42baef312abedb604a401256878c3 SHA-256: 8de820d77620922834f9ca826bd3c24e3c58f35f759b511da7a0b4e67880b662
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an RTF document containing an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). This is strongly indicated by the RTF_EQUATION_EDITOR and RTF_OBJDATA heuristics, along with the ClamAV detection name. The ".objupdate" directive forces the activation of the embedded object, which is designed to execute malicious code. This technique is commonly used to deliver secondary payloads, hence the high confidence in an exploitation for client execution attack pattern.

Heuristics 5

  • 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
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000732.bin rtf-objdata-decoded RTF \objdata at offset 0x732 4153 bytes
SHA-256: a88ed63b285a27e0852e1a5a22b5a0db34610ada906b44b345ced6d49ca8ba3a