Category Archives: Potential Risk of CVE

Sep 2019 Security advisory by Siemens productcert

Preface: Do you think that VPN solutions will reduce the level of network security risks?

Background: On 10th Sep, 2019, Siemens announce that a multiple vulnerabilities in SINEMA connect server. Our attention this time will be focused CVE-2019-13920 and CVE-2019-13922. Refer to attached diagram, the fundamental design of SINEMA and network switch can form VPN to prevent packet sniffing and tamper the network activities. The VPN tunnel between the device and the SINEMA RC Server is established only after successful authentication. However if the design weakness occurs on front end server. It looks that it doesn’t help!

About CVE-2019-13920 – One simple and effective way to prevent it is to generate a random string when the initial action is loaded and send it to the browser. The browser then sends this instruction, and the server validates it before approving the action. This way, malicious websites cannot post action even if they have access to a valid session in a browser.

About CVE-2019-13922 (residual risk) – If we can manage to get the hash of an administrative user since we can then authenticate with higher privileges by performing an attack known as pass the hash.

Should you have interested to know the details, please refer to the url – https://cert-portal.siemens.com/productcert/pdf/ssa-884497.pdf

Deploying cutting-edge technology, it is difficult to avoid vulnerability – cve-2019-16103

Preface: The SD-WAN is a specific application of software-defined networking (SDN) technology applied to WAN connections such as broadband internet, 4G, LTE, or MPLS.The technology deployment consists of QoS and network resiliance.

Product background: EdgeConnect has following features:

  • Extend the micro-segmentation of specific application traffic from the data center to the entire WAN to help maintain security compliance requirements.
  • Tunnel Bonding
  • Identifying applications on the first packet is especially important when branches are deployed behind Network Address Translation (NAT); the correct path must be selected based on the first packet to avoid session interruption.

Vulnerability details: An administrative user with access to the enable menu of the login subshell may enter a hardcoded string to obtain a bash shell on the operation system. The spsadmin and admin accounts have root privileges. The system cli and web service works under root accounts which can be used for privilege escalation.

Observation: Perhaps this vulnerability might let people ignore. But do not contempt this issue because it shown that the user privileges not define well.

Remedy: Fixed in version 8.1.6.x – 8.1.7.x


Vmware – Storm in teacup (Sep 2019)

Preface: In 1894 Damoizeau developed a panoramic stereoscopic camera with twin-lenses, twin-spools and twin -slits.

Background information: With 3D graphics configured for RDS hosts, both applications in application pools and applications running on RDS desktops can display 3D graphics.

Vulnerability details: This vulnerability can be triggered by providing a tamper-evident pixel shader to the AMD ATIDXX64.DLL driver. An attacker can perform an attack from the VMware guest user mode, causing memory corruption on the vmware-vmx.exe process on the host. Successful exploitation of this issue may lead to information disclosure or may allow attackers with normal user privileges to create a denial-of-service condition on the host.

Reminder: Exploitation of this issue require an attacker to have access to a virtual machine with 3D graphics enabled.

Official announcement – https://www.vmware.com/security/advisories/VMSA-2019-0014.html

vmware Security Focus CVE-2019-5532 and CVE-2019-5534

Introduction: Open Virtualization Format. Open Virtualization Format (OVF) is an open standard for packaging and distributing virtual appliances or, more generally, software to be run in virtual machine.

Synopsis: Open Virtualization Format provides the ability to let a virtual appliance and run it on different vendors of virtual machine. For example: Vmware.
Two of the vulnerabilities, CVE-2019-5532 and CVE-2019-5534, are rated “important” by VMware. They are all belongs to OVF technology domain.

  • CVE-2019-5534 – expose login information via the virtual machine’s vAppConfig properties.
  • CVE-2019-5532 – malicious user with access to the log files have view the credentials used to deploy the OVF.

Official announcement: Please refer to the url https://www.vmware.com/security/advisories/VMSA-2019-0013.html

Perhaps more risk will be occured on “OVF” not only the vulnerabilities alert by VMware this week. The OVA files can carry malicious code to any virtual machine OS; even mere data files of a certain complexity can effectively launch exploits.

Staying alert of your hhvm (cve-2019-11925 & cve-2019-11926)

What is HHVM? HHVM is an open-source virtual machine designed for executing programs written in Hack and PHP. The mechanism is convert PHP to bytecode. Then, bytecode translated to machine code at runtime by JIT (just-in-time) compiler.

Vulnerability details: CVE-2019-11925 and CVE2019-11926 found design weakness of the boundary check when processing JPEG APP12 block marker and M_SOFx markers form JPEG marker in the GD extension. It could allow access to out-of-bounds memory via a maliciously constructed invalid JPEG input. See attached diagram for the attack process. The supplier indicates that the defect will only lead to information leakage.

Summary: JPEG file (see specification) contains 2-bytes header (SOI) followed by series of markers, some markers can be followed by data array. Each type of marker has different header format. The bytes where the image is stored follows SOF0 marker (10-bytes length).
‘exif_process_SOFn’ assumes that the JPEG header has at least 6 length. On providing a length < 6, this leads to an out of bounds heap read.

Vendor advisory: https://www.facebook.com/security/advisories/cve-2019-11925

cve-2019-11660 Data protector privilege escalation via omniresolve (Sep 2019)

Prefect: People prefer Veeam because the interface is easier, and Data Protector is difficult in comparison.

Product details: Data protector is a backup and disaster recovery solution for large, complex, and heterogeneous IT environments.

Vulnerability details: A potential vulnerability has been identified in Micro Focus Data Protector. The vulnerability could be exploited by a low-privileged user to execute a custom binary with higher privileges.

Our comment:
Above vulnerability might focus on Data protector server installed on Linux OS platform.
If authorized user exploit the power of SUID/GUID files on Linux, they can enable a file to have one of those bits, to shared the privileges. If a file has a SUID bit to run as root, it has the power to do everything that root can.

Reference: The omniresolve command reads the filesystem structures locating the physical disks (on Windows)
or volumes (on UNIX)on which a filesystem object resides. If the files reside on a logical volume which is a part of a volume group(diskgroup),all volumes in a volume group are displayed.

Status & remedy: versions 10.00, 10.01, 10.02, 10.03, 10.04, 10.10, 10.20, 10.30, 10.40 are affected. Require update Micro Focus Data protector to 2019.08 (A.10.50) or a higher version.

Schneider Electric Security Notification – CVE-2019-6811 (Sep 2019)

Product background: The Modicon Quantum Ethernet I/O (QEIO) automation platform is designed to meet the requirements of both the industrial automation and process industries.

Vulnerability details: An Improper Check for Unusual or Exceptional Conditions (CWE-754) vulnerability exists, which could cause denial of service when the module receives an IP fragmented packet with a length greater than 65535 bytes. The module then requires a power cycle to recover.

Additional info: The maximum packet length for IPv4 = 65,535 bytes but the size is limited due to the physical layers MTU( 1500 for Ethernet). So to send larger packets it would require fragmentation.

IP fragmentation is an Internet Protocol (IP) process that breaks packets into smaller pieces (fragments), so that the resulting pieces can pass through a link with a smaller maximum transmission unit (MTU) than the original packet size. The fragments are reassembled by the receiving host.

Remark: Scapy is a tool to generate your own packets.

Affected Product – Quantum 140 NOE771x1 version 6.9 and earlier.

Remediation: This vulnerability is fixed in version 7.0

CVE-2019-15292 Linux Kernel up to 5.0.8 atalk_proc.c atalk_proc_exit memory corruption

Background: Appletalk support allows your Linux machine to interwork with Apple networks. Below components conduct the specified functions.

  • sysctl_net_atalk.c: sysctl interface to net AppleTalk subsystem.
  • ddp.c: AppleTalk DDP protocol for Ethernet ELAP (ethertalk).
  • atalk_proc.c: proc support for Appletalk

The Use-After-Free vulnerability is related to above three components. Even though you do not use ApplyTalk, attacker by sending a request that submits malicious input to the targeted system. A successful exploit could allow the attacker to execute arbitrary code.

In the Linux kernel version 2.6.23, the /proc/sys/vm/mmap_min_addr tunable was introduced to prevent unprivileged users from creating new memory mappings below the minimum address. To enable it, add or amend the following entry in the /etc/sysctl.conf file: vm.mmap_min_addr = 4096

Security Focus: What is NULL pointer dereference flaws in the Linux? NULL pointer dereference flaws in the Linux kernel can often be abused by a local, unprivileged user to gain root privileges by mapping attacker-controlled data to low memory pages.

But above adjustment cannot resolve these vulnerabilities. It was because if alloc_disk fails in pcd_init_units, cd->disk will be NULL, however in pcd_detect and pcd_exit, it’s not check this before free.It may result a NULL pointer dereference.

Remedy: Kernel.org has released remedy at the following link – https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6377f787aeb945cae7abbb6474798de129e1f3ac

Quick and Dirty – walk through CVE-2019-15846

Preface: Quite a lot of cyber security expertise provides their explanation on vulnerability on Exim (A local or remote attacker can execute programs with root privileges). I will do a quick and dirty way to explain. Should you have interested, please refer below:

a. Connect to Exim with TLS and send an SNI that ends with backslash-null.
*unescaped-backslash bug in string_printing2()

b. We exploit the backslash-null bug in string_interpret_escape().

Hints: Brainstorm on above matter
When you do a malloc, it gives you a pointer to a block of memory in the heap
char *p=malloc(2048) – Virtual memory allocated 2048
strcpy(p,”123”) – Although only 3 bytes are used, the memory still allocates 2048 bytes of physical memory for it.
free(p) – Through the virtual address, find the physical page corresponding to it, release the physical page, and release the linear region.use this heap overflow to overwrite the header of a free malloc chunk.

c. use this heap overflow to overwrite the header of a free malloc chunk.

d. allocate this enlarged malloc chunk, and use it to overwrite large parts of the heap (the already-allocated malloc chunks) with arbitrary data:

e. Overwrite the “id” string: (by overwriting “id” with “/../../../../../../../../etc/passwd”)

Official announcement:

Download and build a fixed version:

    Tarballs: https://ftp.exim.org/pub/exim/exim4/
    Git:      https://github.com/Exim/exim.git
              - tag    exim-4.92.2
              - branch exim-4.92.2+fixes

CIS Center for Internet Security Urge PHP customer aware of Multiple Vulnerabilities in PHP. Because it could allow for Arbitrary Code Execution. Sep 2019

Preface: Network security experts may hesitate to answer a question. What is it? Which programming language is easy to write. But there are no loopholes.

CIS Center for Internet security announcement: Multiple Vulnerabilities in PHP Could Allow for Arbitrary Code Execution

For more information, please refer URL – https://www.cisecurity.org/advisory/multiple-vulnerabilities-in-php-could-allow-for-arbitrary-code-execution_2019-087/

Our Observation: One of the component to Jeopardize your PHP website is the “arbitrary-php-extension”. An experimental has been proofed. After loading custom made PHP extension, each request will be able to execute a piece of your own PHP code. If you need to customize the request argument arbitrary_php to something else, you can modify the value of REQUEST_NAME in (arbitraryphp/extinitial/pre_request.h). Parameter can be find on attached picture.