🟢 CVE-2013-3893

CVE-2013-3893 is a critical use-after-free vulnerability in the `SetMouseCapture` implementation within `mshtml.dll`, a core component of Microsoft Internet Explorer ^[1].

Active Exploitation and Threat Actors

• In the Wild: The vulnerability was actively exploited in the wild as a zero-day before a patch was available ^[2].
• Usage: It was utilized in limited, targeted attacks ^[2]. Research indicated that the threat actors behind these campaigns targeted organizations in the financial industry, with activity observed as early as July 2013, predating the widely reported public disclosure ^[3].

Attack Method and Requirements

• Method: The vulnerability is a use-after-free error, which allows remote attackers to execute arbitrary code ^[1].
• Requirements: Exploitation typically requires a user to visit a specially crafted malicious webpage using a vulnerable version of Internet Explorer ^[1]. It is a remote attack vector that relies on user interaction (navigating to the malicious site).

Impact and Nature of Attacks

• Access/Impact: Successful exploitation provides the attacker with the same user rights as the current logged-in user ^[1]. If the user is logged in with administrative privileges, the attacker could gain full control of the affected system, allowing them to install programs, view, change, or delete data, or create new accounts with full user rights.
• Ransomware vs. Targeted: The vulnerability was primarily associated with targeted espionage-style attacks rather than broad ransomware campaigns ^[2].

Availability of Exploits

• Proof-of-concept code and exploit payloads were developed and utilized by threat actors in the wild during the active exploitation window in 2013 ^[3].

Affected Versions and Mitigation

• Affected Versions: Internet Explorer 6 through 11 were identified as vulnerable ^[1].
• Status: Microsoft addressed the vulnerability in 2013 via security updates (specifically MS13-080) ^[1]. Prior to the full patch, Microsoft released a "Fix it" workaround tool that modified `mshtml.dll` in memory to mitigate the risk ^[2].