Potential CVE-2025-33053 Exploitation via Internet Explorer Diagnostics

CVE-2025-33053 is a vulnerability in Internet Explorer that allows for remote code execution when a user opens a specially crafted URL file. Successful exploitation can allow an attacker to execute arbitrary commands on the victim's system with the privileges of the current user. This is achieved by tricking the user into opening a malicious URL file, potentially delivered via phishing (T1566). The vulnerability can be exploited through the Diagnostics Utility for Internet Explorer (iediagcmd.exe), which spawns child processes to execute commands. Attackers may attempt to masquerade legitimate system processes (T1036) by using system binaries from non-standard locations to evade detection. The vulnerability was disclosed in 2025, and defenders should monitor for exploitation attempts using the techniques outlined below.

Attack Chain

1. Attacker crafts a malicious URL file designed to exploit CVE-2025-33053.
2. The malicious URL file is delivered to the victim via phishing (T1566) or other means.
3. Victim opens the malicious URL file, which triggers the Internet Explorer Diagnostics Utility (iediagcmd.exe) to launch.
4. The exploited iediagcmd.exe process attempts to execute system binaries such as route.exe, netsh.exe, ipconfig.exe, dxdiag.exe, conhost.exe, or makecab.exe from non-standard locations.
5. The attacker leverages these binaries to perform reconnaissance on the system, such as gathering network configuration (ipconfig.exe), or attempt to establish persistence.
6. The attacker may use masquerading techniques (T1036.005) to hide their activity by naming the malicious binaries similarly to legitimate resources.
7. The attacker can use system binary proxy execution (T1218) to perform malicious actions using trusted system tools.
8. The ultimate objective could be lateral movement, data exfiltration, or deployment of ransomware.

Impact

Successful exploitation of CVE-2025-33053 can lead to arbitrary code execution on the victim's system. This could allow attackers to gain initial access to the network, escalate privileges, steal sensitive data, or deploy ransomware. The impact is significant due to the widespread use of Internet Explorer in enterprise environments, even if only for legacy application compatibility. The number of victims will vary based on the attacker's targeting and the success of their phishing campaigns.

Recommendation

• Deploy the Sigma rule "Potential CVE-2025-33053 Exploitation" to your SIEM to detect suspicious child processes of iediagcmd.exe (rule.name).
• Review and update endpoint security policies to restrict the execution of potentially malicious URL files (references).
• Enable Sysmon process creation logging to capture detailed process execution information, which is required for the Sigma rules to function effectively (rules.logsource).
• Monitor network connections originating from suspicious processes spawned by iediagcmd.exe for any unauthorized data exfiltration or communication with known malicious IP addresses (rules.logsource).
• Implement additional monitoring and alerting for similar suspicious activities involving explorer.exe to enhance detection capabilities and prevent recurrence (rules.logsource).