Traps Prevents In-The-Wild VBScript Zero
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2018-8174 | Out-of-Bounds Write RCE in Microsoft Windows VBScript Engine CVE-2018-8174 is an out-of-bounds write (CWE-787) in the Microsoft Windows VBScript engine, caused by the way it handles objects in memory. An attacker triggers it by convincing a user to visit a specially crafted website or open crafted content that invokes the VBScript engine (for example via Internet Explorer or a document preview), requiring user interaction. Successful exploitation yields remote code execution with the privileges of the logged-on user, enabling program installation, data theft and account takeover. All listed Windows client and server releases are affected: Windows 7, 8.1, RT 8.1, Windows 10 (1607-1803), and Windows Server 2008/2008 R2, 2012/2012 R2, 2016. Exploitation is in the wild: the flaw was fixed in the May 2018 Patch Tuesday, is listed in CISA KEV with known ransomware use, and public PoCs (0patch, ExploitDB 44741) and exploit kit usage have been documented; EPSS puts its 30-day exploitation probability at 88.5%. Do: Apply Microsoft's May 2018 security updates (and any later cumulative or Extended Security Updates) to every listed Windows client and server release, as required by the CISA KEV listing, prioritizing internet-reachable and user-facing systems given known ransomware use. Upgrade out-of-support platforms (Windows 7/8.1/RT 8.1, Server 2008/2008 R2, 2012/2012 R2) to supported builds or ensure ESU coverage. As interim mitigation, block VBScript execution in Internet Explorer web zones using Microsoft's documented Group Policy/registry settings, and hunt for prior exploitation on legacy systems. | 7.5 | 88% | KEV ransomware PoC ×2 |
| masshundreds of millions of Windows PCs and servers (affected desktop releases dominated the ~1B+ device Windows install base at disclosure) | |
| CVE-2018-8373 | Memory Corruption RCE in Microsoft Internet Explorer Scripting Engine CVE-2018-8373 is an out-of-bounds write (CWE-787) in the Microsoft scripting engine's handling of objects in memory, which can corrupt memory and enable remote code execution in Internet Explorer 9, 10, and 11. It is triggered when a user is lured to an attacker-crafted web page or script in IE, with no privileges required but user interaction and relatively high attack complexity per the CVSS vector (AV:N/AC:H/UI:R). A successful attacker gains arbitrary code execution in the context of the current user, compromising that workstation's data and credentials. Any Windows system whose users browse with Internet Explorer 9, 10, or 11 was affected, and Microsoft fixed the flaw in its August 2018 Patch Tuesday release. The flaw was exploited as a zero-day in the wild at the time of patching — press coverage describes an in-the-wild VBScript zero-day blocked by endpoint protection — and it was added to CISA's Known Exploited Vulnerabilities catalog on 2022-03-25; EPSS places the 30-day exploitation probability at 61.9% (99th percentile). Do: Apply Microsoft's August 2018 security updates for Internet Explorer on all supported Windows versions — the required action listed in the CISA KEV — and verify patch deployment via WSUS/SCCM/Intune across end-user workstations and RDS/browsing hosts. As interim mitigation, consider Microsoft's documented workaround of disabling VBScript execution in IE via feature-control keys and steer users away from IE for web browsing. Finally, migrate any remaining IE9/10/11 usage to Microsoft Edge (using IE mode for legacy sites), since IE11 is retired and this flaw is confirmed exploited in the wild. | 7.5 | 62% | KEV |
| masshundreds of millions of Windows devices (IE9–11 shipped with Windows; IE11 present by default on Windows 7/8.1/10) |
Indicators of compromiseauto-extracted · verify before use · export allAll →
| Type | Indicator | Context |
|---|---|---|
| domain | windows-updater.net | ied. The exploit was served on a malicious web host: hxxp://windows-updater[.]net/realmuto/wood.php?who=1?????? which was linked to the Dar |
| url | http://windows-updater[ | es applied. The exploit was served on a malicious web host: hxxp://windows-updater[.]net/realmuto/wood.php?who=1?????? which was linked to the |
Full article449 words · extracted from unit42.paloaltonetworks.com · click to collapse
On August 15, Trend Micro published a blog post detailing a high-risk vulnerability in the VBScript Engine of Microsoft Internet Explorer being exploited in-the-wild (CVE-2018-8373). This vulnerability still affects endpoints running the latest versions of Internet Explorer and Windows which do not have the relevant patches applied.
The exploit was served on a malicious web host: hxxp://windows-updater[.]net/realmuto/wood.php?who=1?????? which was linked to the DarkHotel APT campaign by Qihoo 360, and this actor also exploited another VBScript vulnerability earlier this year (CVE-2018-8174). The preliminary payload was also analyzed thoroughly by Qihoo 360, and is dubbed zlib1.dll.
Figure 1. The attack flow as observed in the malicious sample
In Figure 1 we show the attack flow as observed in the malicious sample. First, the victim browses to the exploit URL in the malicious web host (1). The returned webpage contains malicious VBScript which exploits a UAF in vbscript.dll. This exploit implements a RW primitive, uses it to locate and leak the addresses of exported functions, creates a fake CONTEXT structure, and then uses NtContinue to jump to VirtualProtect on the shellcode and directly return to it afterwards (2). The exploitation phase is thoroughly analyzed in Trend Micro’s post.
The shellcode then proceeds to download an initial payload (DLL) from the same malicious web host (hxxp://windows-updater[.]net/realmuto/wood.php?var=xxx&name=dr.john&q=yyy&d=z) to a temporary file (3), decode it to another temporary file (4) and load it using LoadLibrary (5).
On x86 systems, this payload drops itself to %ALLUSERSPROFILE%\zlib1.dll (6), implements a UAC-bypass using mmc.exe (7) and then re-runs itself using rundll32.exe (8). On x64 systems, it runs its main logic directly from iexplore.exe.
The main logic of the initial payload sends the infected computer configuration and downloads a secondary payload from the same host: hxxp://windows-updater[.]net/dragon/config-donkey.php?inst=xxx&name=yyy (9), decodes it and reflectively loads it (10).
We were not able to retrieve samples of the secondary payload for further analysis.
How Traps Prevents this Threat
Palo Alto Networks Traps advanced endpoint protection offers multiple layers of malware and exploit prevention to protect against such complex threats.
Traps prevents a few different and independent techniques of the described exploit using its anti-exploit capabilities. In addition, Traps malware examination flow and local analysis via machine learning, and WildFire integration also prevents the malicious payload from executing at different phases of the attack. In Figure 1 we have marked with the Traps logo different points in the exploitation flow in which Traps would have prevented the attack flow from going forward.
Moreover, even older versions of Traps released years ago would have prevented this exploit from running without applying any special configuration or policy updates.
AutoFocus customers can track this actor via the DarkHotel tag.
Text extracted automatically; images, tables and formatting may be missing. Original: https://unit42.paloaltonetworks.com/unit42-traps-prevents-wild-vbscript-zero-day-exploit-internet-explorer/