Mysterious hackers ingenuously reveal two Zero
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2018-4990 | Double Free RCE in Adobe Acrobat and Reader CVE-2018-4990 is a double free (CWE-415) memory-corruption vulnerability in Adobe Acrobat and Reader, in which the application frees the same memory allocation twice while handling a crafted PDF document. An attacker who convinces a user on a vulnerable build to open a malicious PDF (e.g., via email attachment or web download) can corrupt heap memory and achieve remote code execution in the context of the logged-in user. Anyone running vulnerable releases of Adobe Acrobat or Reader is affected; the provided data does not enumerate specific version ranges, so unpatched builds from the disclosure era should be treated as potentially vulnerable. The flaw is listed in CISA's Known Exploited Vulnerabilities catalog (added 2022-06-08), confirming exploitation in the wild; no public proof-of-concept is known, ransomware association is unknown, and EPSS assigns a high 36.6% probability of exploitation within 30 days. Do: Apply Adobe's security updates to Acrobat and Reader per vendor instructions, as required by the CISA KEV catalog, and identify any legacy or unmanaged PDF reader installs that no longer receive updates. Given the elevated EPSS score and KEV listing, prioritize patching high-value and frequently emailed endpoints, and review endpoint/mail-gateway telemetry for PDF-borne exploitation activity. | 8.8 | 36% | KEV |
| mass≈ hundreds of millions of users (Acrobat/Reader is the dominant desktop PDF reader; only unpatched builds are vulnerable) | |
| CVE-2018-8120 | Local Privilege Escalation in Microsoft Win32k (Windows 7 / Server 2008) CVE-2018-8120 is an elevation of privilege flaw in the Microsoft Windows Win32k kernel component, which fails to properly handle objects in memory. A local attacker who already has the ability to run code with low privileges on the machine must execute a specially crafted application that triggers the faulty object handling, allowing code to run in kernel mode. Successful exploitation yields elevated (SYSTEM-level) privileges and full control of the host, and it is commonly chained with a remote code execution or browser exploit, or used by malware — including ransomware — to deepen a compromise. Only systems running Windows 7, Windows Server 2008, or Windows Server 2008 R2 with unpatched Win32k are affected. The bug was exploited as a zero-day (reportedly by the ScarCruft APT group) before being fixed in May 2018 Patch Tuesday, a public PoC is available, and it was added to CISA's Known Exploited Vulnerabilities catalog in March 2022 with known ransomware use. Do: Apply Microsoft's May 2018 security updates or later cumulative updates for Windows 7, Windows Server 2008, and Windows Server 2008 R2, prioritizing this KEV-listed flaw per the CISA required action. Systems beyond end of support that are not receiving Extended Security Updates should be migrated to a supported Windows version or isolated, since they remain permanently exposed to known APT and ransomware tooling. Review hosts for signs of local privilege escalation and ensure any RCE entry vector (browser, file format, or service exploit) is also patched, as this bug is typically used to escalate an initial foothold. | 7.0 | 73% | KEV ransomware PoC |
| mass≈ hundreds of millions of Windows 7 desktops plus widespread Windows Server 2008/2008 R2 deployments worldwide |
Full article577 words · extracted from securityaffairs.com · click to collapse
Mysterious hackers ingenuously reveal two zero-days to the security community, experts collaborated to promptly fix them.
Anton Cherepanov, security expert form ESET researcher, discovered two zero-days while analyzing a malicious PDF, according to the researcher the mysterious hacker(s) were still working on the exploits.
The malicious PDF was discovered late in March 2018 (Two suspicious PDF samples zero-day 1, zero-day 2), the analysis of the document revealed it was exploiting two previously unknown vulnerabilities, a remote-code execution vulnerability in Adobe Reader and a Windows privilege escalation flaw.
“The use of the combined vulnerabilities is extremely powerful, as it allows an attacker to execute arbitrary code with the highest possible privileges on the vulnerable target, and with only the most minimal of user interaction. APT groups regularly use such combinations to perform their attacks, such as in the Sednit campaign from last year.” reads the analysis published by ESET.
“The sample does not contain a final payload, which may suggest that it was caught during its early development stages,” Cherepanov said.
ESET shared its discovery with the Microsoft Security Response Center, Windows Defender ATP research team, and Adobe Product Security Incident Response Team as they fixed these bugs.
The two zero-days were tracked as CVE-2018-4990, that affected Adobe Acrobat/Reader PDF viewer, and as CVE-2018-8120 that affected the Win32k component of Windows.
By chaining the two vulnerabilities it was possible to escape the Adobe’s sandbox protection and execute arbitrary code inside Adobe Acrobat/Reader.
“The malicious PDF sample embeds JavaScript code that controls the whole exploitation process. Once the PDF file is opened, the JavaScript code is executed,” states the report published by ESET.
Below the steps composing the attack chain:
- The victim receives and opens a weaponized PDF file
- Once the user opened the PDF, a malicious JavaScript code will execute.
- JavaScript code manipulates a button object
- The Button object contains a specially-crafted JPEG2000 image, triggers a double-free vulnerability in Adobe Acrobat/Reader.
- JavaScript code uses heap-spray techniques to obtain read and write memory access
- JavaScript code then interacts with Adobe Reader’s JavaScript engine
- The attacker uses the engine’s native assembly instructions (ROP gadgets) to execute its own native shellcode.
- Shellcode initializes a PE file embedded in the PDF
- Once the attacker has exploited the Adobe Reader vulnerability, he will leverage the Window zero-day flaw to escape the sandbox. The Microsoft Win32k zero-day allows the attacker to elevate the privilege of the PE file to run, which is run in kernel mode, escaping the Adobe Acrobat/Reader sandbox and gaining system-level access.
Even if the chain of the zero-days could be very dangerous, the developers allowed the security community to detect them by uploading it to a known virus scanning engine aiming to test its evasion capability.
The two zero-days have been already patched, Microsoft addressed the CVE-2018-8120 with the release of the May 2018 Patch Tuesday, Adobe patched the CVE-2018-4990 this week.
“Initially, ESET researchers discovered the PDF sample when it was uploaded to a public repository of malicious samples. The sample does not contain a final payload, which may suggest that it was caught during its early development stages.” concludes the report.
“Even though the sample does not contain a real malicious final payload, which may suggest that it was caught during its early development stages, the author(s) demonstrated a high level of skills in vulnerability discovery and exploit writing.”
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(Security Affairs – zero-days, hacking)
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Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/72584/hacking/zero-days-exploits.html