Cloaked and Covert: Uncovering UNC3886 Espionage Operations
In January 2024, Mandiant published a blog post detailing UNC3886's activities exploiting CVE-2023-34048 (VMware vCenter) since late 2021.
2 passages name itOriginal (opens in a new tab) ↗
CVE-2023-34048 KEVPublic exploit Critical · 9.8 EPSS 99.2%
VMware vCenter Server Out-of-Bounds Write Vulnerability
VMware · vCenter Server
Summary
VMware vCenter Server contains an out-of-bounds write flaw in its implementation of the DCERPC protocol. The vulnerable code sits in the vCenter Server product itself, within the protocol handling component. An attacker with network access to vCenter Server, requiring no authentication and no user interaction, can trigger the out-of-bounds write, which could lead to remote code execution.
Official description · NVD
vCenter Server contains an out-of-bounds write vulnerability in the implementation of the DCERPC protocol. A malicious actor with network access to vCenter Server may trigger an out-of-bounds write potentially leading to remote code execution.
Priority scorePatchfirst’s 0 to 100 ranking. It adds points for CISA KEV listing, ransomware use, EPSS, threat reports, public exploit code and CVSS. Every CVE page shows the breakdown. Breakdown
73.7 / 100
- Exploited
- Yes, in CISA KEV
- Reports
- 1
- Tactics
- 1/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.What can follow
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 3 months after disclosure.
- Disclosedday 0
- First seen exploitedVulnCheck KEV evidence+3 mo
- Added to CISA KEVEU database agrees+3 mo
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
1 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order 1Resource DevelopmentTA0042
Malware T1588.001
MITRE CTID mapping of the KEV entry · follow-on activity
This vulnerability is exploited by an adversary who has already gained network access to the vCenter Server. The adversary sends a crafted payload to the server that has a vulnerable DCERPC protocol and causes an out-of-bounds write on the jmp rax instruction. Adversary group UNC3886 has been attributed to leveraging this vulnerability in the wild to establish a backdoor in victim vCenter servers.
Lower-confidence links (1)
These come from early or generic mappings, text matching, or contradict this CVE’s details (for example a public-facing technique on a bug that needs a user to open a file). Shown for completeness.
- Exploitation for Client ExecutionT1203 server-side bug exploitable without user interaction; client-execution technique does not fit
Detection
0 rules for this CVE · 1 general rule for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2023-34048 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
MalwareT1588.0011 general rule
- Relevant ClamAV Messagehighstable
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Named in 1 threat report1 reportGoogle Mandiant
Reports are matched by finding the exact id CVE-2023-34048 in their text; nobody has reviewed the match. One passage is shown per report, at most 320 characters, linked to the original.
Also mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
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