MSXML Uninitialized Memory Corruption Vulnerability
CVE-2012-1889 is a remote code execution vulnerability in Microsoft XML Core Services (MSXML) 3.0, 4.0, 5.0, and 6.0. The flaw is described by Microsoft as an uninitialized memory corruption issue that occurs when MSXML accesses or uses an object in memory that has not been properly initialized. An attacker can trigger the vulnerability by causing a victim to view specially crafted web content that invokes MSXML through Internet Explorer. Microsoft bulletin MS12-043 states that the issue is fixed by modifying how MSXML initializes objects in memory before use. The vulnerability was publicly disclosed and, at the time of bulletin release, Microsoft reported limited targeted exploitation in the wild.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository is a proof-of-concept (PoC) for CVE-2012-1889, a critical vulnerability in the Microsoft XML Core Services (MSXML) component used by Internet Explorer 8 on Windows. The repository contains five files: two module information dumps (1.txt, 2.txt), a README.md (in Chinese) describing the exploit components, a test PoC HTML file (cve-2012-1889-test-poc.html), and a log file (log.txt) from the mona.py ROP gadget generator. The main exploit vector is a malicious HTML file that instantiates a vulnerable ActiveX control (classid:f6D90f11-9c73-11d3-b32e-00C04f990bb4) and triggers the vulnerability via crafted JavaScript. The exploit relies on a non-ASLR module (MSVCR71.dll from Java 6u37) to build a ROP chain for bypassing DEP and achieving code execution. The log.txt file details the ROP chain construction for VirtualProtect/VirtualAlloc, confirming the exploit's intent to execute arbitrary shellcode. The repository is structured as a learning or demonstration project, with supporting files for debugging and ROP chain generation, but the main exploit logic is in the HTML/JavaScript code. No weaponized payload is included, but the PoC demonstrates reliable exploitation of the vulnerability in a controlled environment.
Affected products & vendors
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
8 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A remote code execution vulnerability in Microsoft XML Core Services caused by improper handling of objects in memory (uninitialized memory corruption). Successful exploitation could let an attacker execute code if a user visits a specially crafted webpage, potentially leading to full system compromise under the user's context.
A remote code execution vulnerability in Microsoft XML Core Services (MSXML) caused by access to an object in memory that has not been initialized.
A remote code execution vulnerability in Microsoft XML Core Services caused by uninitialized memory corruption.
A specific vulnerability used in exploit kits according to the table.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.