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What does buffer underflow in C/C++ programs mean?

What does buffer underflow in C/C++ programs mean?

1. Buffer underflow Buffer overflow was analyzed in the previous topic (see Issue 7). This article describes another situation of buffer overflow - buffer underflow. The causes of buffer overflow introduced in the buffer overflow topic also apply to buffer underflow, so we will not go into details in this article. Simply put, buffer underflow means that when the filling data overflows, the overflow part covers the lower-level buffer. This article mainly describes the problem from the hazards of buffer underflow, its performance in source code, and how to fix it. 2. The harm of buffer underflow Buffer underflow is a very serious type of vulnerability in C/C++ programs, which may cause program crashes, execution of malicious code and other consequences. From January to October 2018, there were 49 CVEs

May 29, 2023 pm 12:22 PM
C++ C语言
How to understand ip port protocol

How to understand ip port protocol

Computers on the Internet will have a unique 32-bit address. When we access the server through the IP address, the local area network also has a reserved IP address starting with 192/10/172. The IP address of the LAN is also the only NAT mode. The IP of the computer host is unique in the LAN. The selected NAT mode creates a virtual machine, and the virtual machine is a new LAN (private network). The teacher's machine IP is a simple concept of port 192.168.33.128. 192.168.33.128 represents a host, but there may be many services on the host. Different service functions on a host are distinguished by ports, and then let external personnel access. SSH remote connection service 22

May 29, 2023 am 11:22 AM
ip
How to analyze Haproxy port reuse

How to analyze Haproxy port reuse

Author of this article: Spark (Ms08067 intranet security team member) 1. Overview Haproxy is a high-performance load balancing proxy software developed in C language. It provides tcp and http application proxies. It is free, fast and reliable. Similar to frp, it can be run using a configuration file + a server. Advantages: Large-scale business field applications widely support four-layer proxies (transport layer) and seven-layer proxies (application layer). Support ACL (access control list), and can flexibly configure routing windows. It can be run after compiling with cygwin (can be cross-platform) access control list (AccessControlLists, ACL) is a list of commands applied to the router interface. These command lists

May 29, 2023 am 09:25 AM
haproxy
Example analysis of Thin Provision

Example analysis of Thin Provision

Thin provisioning (ThinProvision), sometimes called "oversubscription", is an important emerging storage technology. This article introduces thin provisioning, its working principle, usage limitations, and some usage suggestions. If the storage space used by the application is full, it will crash. Therefore, storage administrators often allocate more storage capacity than the application actually requires to avoid any potential application failure. This approach provides "headroom" for future growth and reduces the risk of application failure. But it requires more physical disk capacity than actual, causing waste. Thin provisioning software eliminates the need to allocate unused disk capacity in advance, resulting in higher overall storage utilization.

May 28, 2023 pm 08:47 PM
thin provision
What does shellcode mean?

What does shellcode mean?

1. Introduction to pre-knowledge points of shellcode programming. What is shellcode? The essence of shellcode is actually a piece of assembly code that can run independently. It does not have any file structure, it does not rely on any compilation environment, and cannot be double-clicked to run like an exe. You can refer to Baidu for a detailed introduction to shellcode, so I won’t go into details here. Why write your own shellcode? Because I have done a lot of penetration in the past six months, the shellcodes used are all generated by CS or MSF, but the shellcode automatically generated by the tool is dead after all, and there is no way to expand the function by yourself. Another example is that you know a new vulnerability, but the vulnerability is Using POC can only pop up a calculation

May 28, 2023 pm 03:01 PM
shellcode
What to do if HP APA mode setting causes packet loss for dual network cards

What to do if HP APA mode setting causes packet loss for dual network cards

1. Problem Description A user reported that HP minicomputer system access is very slow. 2. Alarm information Log in to your host scp3 through dial-up and check the relevant logs, including: syslog, eventlog, networklog, bdf, top, glance, ts99, crash, but no alarm or error was found. 3. Analyze the cause of the problem. This phenomenon has occurred on this host many times a year ago. After a comprehensive inspection of the host and network, no abnormalities were found. After restarting the host, the fault was restored. This time log in to your host scp3 through dial-up again and check the relevant logs, including: syslog, eventlog, networklog, bdf, top, g

May 28, 2023 pm 02:16 PM
apa hp
How to configure H3C_ ComwareV7_L2TP

How to configure H3C_ ComwareV7_L2TP

1. Check the device version FW_1030]disversionH3CComwareSoftware,Version7.1.054,Ess9308P05Copyright(c)2004-2015HangzhouH3CTech.Co.,Ltd.Allrightsreserved.2.Configure L2TPl2tpenable//Globally enable L2TPl2tp-group1modelnsallowl2tpvirtual-template1undotunnelau thentication//Do not enable tunnel authentication ippooll2tp17

May 28, 2023 pm 01:58 PM
h3c ComwareV7 l2tp
How to implement firewall NAT control analysis

How to implement firewall NAT control analysis

one. NAT classification NATNo-pat: Similar to Cisco's dynamic conversion, it only converts the source IP address and network address, but does not convert the port. It is a many-to-many conversion and cannot save public IP addresses. It uses less NAPT: (Network address and port translation ) Similar to Cisco's PAT conversion, NAPT converts the source address of the message and converts the source port. The outbound interface address: (Easy-IP) conversion method is simple, the same as NAPT, that is, converts the source address and source port. It is a multi-purpose method. One-to-one conversion SmartNAT (intelligent conversion): NAPT conversion by reserving a public network address Triplet NAT: a conversion related to the source IP address, source du port and protocol type Two, black hole routing source address conversion

May 28, 2023 pm 01:04 PM
防火墙 nat
What are the 8 rules for good APP testing?

What are the 8 rules for good APP testing?

When it comes to software testing, testers definitely think of checking files, functionality, APIs, performance and determining if the software is safe, among other things about a specific part of the software. But for mobile testing, testers have to consider mobile-related features based on user mobile usage patterns. The following mainly talks about mobile testing. For the mobile phone project (application software) of the product, it is mainly system testing. For system testing of mobile application software APP, we usually carry out it from the following perspectives: functional module testing, compatibility testing, installation and uninstallation testing, software update testing, performance testing, user experience testing, cross-event testing, user interface Testing etc. As a software quality assurance manager, I focus on iPhone, Android,

May 28, 2023 pm 12:48 PM
App
How to export libraries needed by the project in Python

How to export libraries needed by the project in Python

Enter the command: pipfreeze>requirements.txt. The content of the file generated is as follows: asgiref==3.4.0Django==3.2.4django-debug-toolbar==3.2.1django-redis==5.0.0Pillow==8.3.0PyMySQL==1.0. 2pytz==2021.1redis==3.5.3sqlparse==0.4.1typing-extensions==3.10.0.0

May 28, 2023 am 11:16 AM
Python
How to get SickOS 1.2 Flag

How to get SickOS 1.2 Flag

The experimental environment is as follows: Basic idea: NetworkScanning (network scanning Netdiscover, Nmap) Directorybrute-force (website directory scanning dirb) FindHTTPOptions:PUT (find HTTP options curl) GeneratePHPBackdoor (generate php backdoor Msfvenom) Uploadandexecuteabackdoor (upload php backdoor) Reverseconnection (Metasploit) PrivilegeEscalation(cronjob)Importpyt

May 27, 2023 pm 10:40 PM
SickOS Flag
Example analysis of MSSQL backdoor from Winnti hacker group

Example analysis of MSSQL backdoor from Winnti hacker group

For some time, ESET researchers have been tracking the activities of Winnti, a group that has been active since 2012 and has targeted the video game and software industry supply chains. Recently, a previously undocumented backdoor was discovered that targets Microsoft SQL (MSSQL). This backdoor bears many similarities to the PortReuse backdoor, another tool used by WinntiGroup and first documented in October 2019. This year, a new backdoor sample, skip-2.0, was detected. The author is a member of the winnti organization. This backdoor targets MSSQL Server 11 and 12 and allows attackers to use magi

May 27, 2023 pm 09:04 PM
mssql
How to use vulnerability scanning software OpenVas

How to use vulnerability scanning software OpenVas

Simply put, openvas is an open source vulnerability detection and scanning software openvas-manager (openvasmd) 9390 openvas-scanner (openvassd) 9391 Greenbonesecurity assistant (gsad) 9392 In fact, the installation is very simple, but it took me a long time to do it for the first time. Mainly the installation script and detection script http://www.openvas.org/install-packages.html This is the download address, the initial state of package installation, close iptables and selinux#wget-q-O-http:

May 27, 2023 pm 07:22 PM
openvas
Example analysis of using ZoomEye to find APT attacks

Example analysis of using ZoomEye to find APT attacks

The data online on ZoomEye is in overwrite and update mode, which means that if the data is not scanned in the second scan, the updated data will not be overwritten. The data on ZoomEye will retain the banner data obtained in the first scan. This mechanism is here In fact, there is a good scene fit in the traceability of this kind of malicious attack: the download servers used by malicious attacks such as Botnet, APT and other attacks are usually directly deactivated and discarded after being discovered. Of course, some are hacked targets, and they are also very violent. Go offline directly! Therefore, many attack sites are likely to be cached online by ZoomEye. Of course, with the data provided in the ZoomEye history api, you can query the number of banners obtained by each scan regardless of whether you cover it or not.

May 27, 2023 pm 07:19 PM
apt ZoomEye

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