Malicious RTF — malware analysis report

Static analysis result for SHA-256 cc822680ea4d3034…

MALICIOUS

RTF

302.0 KB First seen: 2019-03-10
MD5: 693da29256d42b55e5342ff3bb585c40 SHA-1: 250745f98c75a89c44f8e893eb766a67b2924562 SHA-256: cc822680ea4d303412bcbec747cfbf87d96d65a1f51bd809fad07a8a89eb6cc1
300 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object with a CLSID indicative of Microsoft Equation Editor. Heuristics confirm the presence of a payload likely exploiting CVE-2017-11882, which allows for arbitrary code execution. This technique is commonly used in spearphishing attachments to deliver further malicious content.

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.

FilenameKindSourceSize
objdata_00_off0000003b.bin rtf-objdata-decoded RTF \objdata at offset 0x3B 100408 bytes
SHA-256: 8ac7d73307251e8c4b72254aa27ada723f48e6c504401d9ab24e0c54ec394016

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