Securing Linux systems and applications; understanding Linux security features.

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Minimal working configuration for reasonable security in openssh on Linux [duplicate]

I want to connect from my laptop to home server (both run some Linux; notice I explicitly want my user to be able to become root, in order e.g. to install new software): the server has the following ...
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151 views

Is that possible for Linux and windows machines to be infected with KeRanger ransomware?

According to theguardian The Transmission site offers the open source software that was infected with the ransomware called KeRanger malware, it's programmed to encrypt files on an infected personal ...
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3answers
566 views

TSource Engine Query DDoS attack

My gaming machine is under DDoS attack and when I used Wireshark I found the following string "TSource Engine Query" in all UDP packets coming from random IP's. I found using Google that some gaming ...
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3answers
299 views

How to (further) ensure SSH security?

I set up my Linux Ubuntu machine as an SSH server through no-ip.com and it works great. Recently I discovered the command, sudo lastb -ad -F -w which outputs a log of the most recent failed SSH ...
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30 views

How to know who and when files and folders have been deleted in CentOS? [duplicate]

I have a dedicated web server and there is some files and folders have been deleted from my client's sub-domain accidentally and there are more than one user mange the client site. How to know who ...
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317 views

RAM memory data remanence and double boot, risky?

I wonder if my setup can be risky. To give a good starting point for answers I would briefly sketch the situation setup: double boot system GNU/Linux and Microsoft Windows GNU/Linux is on 2 ...
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3answers
6k views

Pitfalls of SSD encryption

Encrypting an SSD is a process that is sometimes warned should be done with caution. E.g. http://en.gentoo-wiki.com/wiki/DM-Crypt_with_LUKS mentions how the SSD may keep hidden space used for wear ...
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2answers
117 views

Don't encrypt the hard drive, but make it impossible to change things without a password?

I recently bought an SSD drive and realized that my CPU (Celeron 1007U - has no AES instructions) cannot really keep up encrypting it and the SSD doesn't have hardware encryption built in. This made ...
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321 views

Code Vulnerability in Shell script

I was given an assignment for my Computer Security class. We we were given a piece of code to analyze and determine the vulnerabilities that it might have. #!/bin/sh # shell script to create a copy ...
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2answers
26 views

Privilege escalation if the privileged ID is known

If I know the ID of a group, whose privilege is higher than mine, is it possible for me to execute programs using that group ID? If so, how do I do it? If not, why not? Will appreciate all answers.
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493 views

Is symlink race a very common vulnerability in UNIX systems

As far as I know, when I am creating a new file or directory in a directory that can be written by multiple users (and thus an adversary can have made a symlink there), the only way to protect myself ...
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444 views

Fishy: VMware sends all traffic through akamai

I'm running Linux inside of VMware on the Mac, and on Linux I'm running a program that has connections open to perhaps 4 different machines. On the OS/X side however VMware has only 1 active network ...
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1answer
91 views

What are the potential privacy issues in using a TPM chip with GNU/Linux

I'm planning to buy a TPM module to bring more security in my system (GNU/Linux, dm-crypt/LUKS, SED) but I'm not sure with the big debate around it. What are the (possible) privacy concerns in using ...
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24 views

using “mount -o bind” in chroot

I have to provide a few, reasonably complete, chrooted ssh accesses to a very small system where disk space is at a premium. I was considering doing something along the lines: mkdir -p newroot/usr ...
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195 views

Why should one bother encrypting the harddisk in linux if one can easily recover the root password?

If you have physical access to a machine, it's pretty straightforward to recover the root password thereby skipping the whole point of having an encrypted drive. Am I missing something here? EDIT: ...
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2answers
150 views

How could hackers get access to directory after hacking Wordpress at LinuxMint.com?

I am sure many have seen the news of the hack at Linux Mint. The ISOs were changed on 20th Feb with backdoored ISOs. They gained access via the LinuxMint Wordpress blog installation. How could they ...
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2answers
253 views

Can CVE-2015-7704 - ntpd kiss-of-death affect NTP time servers or just clients?

As the ntp.conf file on a linux server can be setup to allow the system to act as both a client to the public servers and a time server source for local systems am I correct in assuming that it (the "...
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1answer
221 views

Linux - user can be in forbidden directory if su to it from user with access - is this concerning?

I was in a directory on CentOS as user1 (root in this case) and then did su to user2 which cannot normally get to that directory due to lack of "execute" permission on a parent directory, but as user2 ...
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4answers
1k views

Is it possible to USB whitelist in Linux?

After watching Black Hat's presentation on the fundamental problems with USB "security", I'm wondering if there's a way to do USB whitelisting in Linux. Is there currently a mechanism that will allow ...
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5answers
2k views

I don't recognise my DNS server's address: does this mean I am compromised?

I'm using the Ubuntu GNOME Linux distribution as my desktop. Recently, it became impossible for me to connect to the Internet with it. When I checked its network settings, I saw that the DNS address ...
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1answer
531 views

GNU C Library getaddrinfo() Flaw

As you probably already know, this Tuesday a potentially catastrophic flaw has been identified on glibc function called getaddrinfo(), which performs domain name lookups, contains a buffer overflow ...
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1answer
149 views

What are the advantages and disadvantages of installing an operating system through network? [duplicate]

Netboot is a technology that allows a computer to boot through the network, instead of starting on a hard drive, USB stick or DVD, it connects to a remote server to retrieve a disk image to start. It ...
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1answer
81 views

Will installing a Graphical User Interface in a server be a security problem?

I'm not a CLI-lover, sometimes I prefer to do some tasks in a server using a GUI rather than using the CLI (it speeds up my work), but I don't know if installing a GUI and accessing it using VNC and ...
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2answers
185 views

A question about arpspoof command

The arpspoof command will spoof default_router_ip's MAC address on all victims in the subnet arpspoof -i <NIC> <default_router_ip> How does it fool the router about the MAC addresses ...
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2answers
85 views

Making a file immutable (against kernel exploits)

I'd like to know how to make files completely immutable. "Completely" refers in this case to: immutable while the system is running. I could live with something like physical access where someone e.g ...
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Is that a way break Linux user password by bypassing grub protected?

The best way to delve into others Linux machine is by editing the grub. Many will start by, editing the line ro quite splash as rw init=/bin/bash during the startup (usually by pressing button e on ...
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Where can i find information about Ipsec Xfrm framework?

I have searched online and found very little information about the ipsec xfrm framework, including the book Networking implementation and Theory.. Where can i get more information about xfrm ...
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1answer
63 views

Linux distribution on USB stick used to banking for begginers [closed]

Is it good idea to use up-to-date Linux on USB stick instead liveCD to online banking? What is the best Linux distribution for not advanced people who commonly use Windows to make online payments ...
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61 views

OSSEC error “agent_control(1750): ERROR: No remote connection configured. Exiting”

I am new to OSSEC and trying to figure the tool to deploy it. I have an ubuntu server where I downloaded and installed the security onion packages. I have a few windows systems which I would like to ...
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1answer
56 views

Open Root File Using Other Users “.bashrc -> .profile” [closed]

If I have access to .bashrc -> .profile for another user which is owned by root with lrwxrwxrwx permissions How could I capture /root/flag.txt? It's a Live CD. Thanks
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1answer
186 views

Return-to-libc attack with the argument read from registers (EDI/RDI)

I've read that to make a successful return-to-libc attack, the attacker should store the address of the command (for example /bin/sh) in the stack exactly after the return address of the system ...
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34 views

rpm package info leak?

On Linux, rpm -qi <package-name> command would display the package info, which would contain information of build machine - Build Host :<host-name> Does this pose any security risk? Is ...
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223 views

IPtables Linux Firewall and IPsec traffic

Can iptables filter out incoming datagrams that are IPSec-tunneled packets going to port 25?
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Is cryptsetup luksFormat -y --cipher aes-xts-plain --key-size 512 /dev/sdax a insecure setup for luks [duplicate]

Is cryptsetup luksFormat -y --cipher aes-xts-plain --key-size 512 /dev/sdax insecure. If so why and what setup would be good for keeping corporate information safe?
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1answer
5k views

What is real-world impact of CVE-2016-0728 (Linux Kernel Vulnerability)

Today emerged report about another serious vulnerability in opensource world, CVE-2016-0728. It is local privilege escalation in Linux kernel 3.8+. What are the the possible real-world exploitation, ...
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19 views

Linux equivalent to Windows WriteProtect key in the registry for a software based write blocker?

I unfortunately don't have access to a physical write blocker and am looking for a software based write blocker in Linux. In Windows this can be achieved by modifying the registry and setting a DWORD ...
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1answer
141 views

Linux responds to ARP requests for other interfaces - could this be a security vulnerability?

Linux responds to ARP requests on all interfaces by default. To explain, say you have this setup: Client 1 ---> [eth1] server [eth0] <--- Client 2 And the server's eth1 IP is 192.168.1.1 and ...
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65 views

XCCDF check with SCE - Suse Linux Enterprise Server 11

I have written some compliance checks for Red Hat based systems with XCCDF. Some of my checks are OVAL definitions others are shell-scripts. It works great. The same checks don't work on an SLES 11 ...
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5answers
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Should I use a second/dedicated IP address for SSH?

When running a public web server (e.g., with Apache), I've heard it's recommended to bind SSH to a second IP address, different from the one Apache is listening to. But for me it seems like this is ...
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1answer
441 views

samdump2 Error reading ControlSet: _RegOpenKey

I copied both SAM and SYSTEM files from my Windows7 OS, and then used this command to read the content of the SAM file samdump2 SAM SYSTEM > mdp_chiffres.txt, but i'm getting this error Error ...
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1answer
112 views

Yersinia raw packet

I'm using Yersinia to pentest my network. There are two options send raw packet and creating DHCP rogue server I don't understand fully. Can someone explain the meaning of these options?
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2answers
128 views

Linux kernel security bugs and hardening Ubuntu? [closed]

I recently read some article about the linux kernel having vulnerabilities, I can't recall exactly where. Being new to linux, do you guys have some references on how I should prevent remote access to ...
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2answers
127 views

Security implications of android rooting

I know this question has been asked many times, but I didn't see a clear answer to it from security experts, or it is from several years ago and things might have changed. My question is double: ...
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5answers
5k views

Java SecureRandom doesn't block? How?

I know from experience that reading from /dev/random blocks when the Linux kernel entropy pool runs out of entropy. Also, I've seen many articles and blog entries stating that when running on Linux, ...
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1answer
138 views

Online vs offline backups [closed]

Up to this point I was using physical hard drives for backups, typically using dm_crypt as mentioned here. If online storage is used instead, and the provider cannot be trusted how much should the ...
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2answers
172 views

Secure Android app development [closed]

I'm beginning with Android App development and I want to make sure that I'm taking the proper security precautions since most apps will handle sensitive data. What security precautions should be ...
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1answer
59 views

Is it safe to host passwordless web applications/software with web GUI in Virtual Machines

I have a Linux Mint Virtual Machine which I use quite a lot with my Windows host. I have lots of Software installed there (mostly with web GUI so I can access them from host easily). So I am ...
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1answer
89 views

Can a brute force attack be certainly prevented on a unix/linux shell?

I've been getting kind of curious about computer security. I know brute force has been discussed a fair bit on Stack, but I want to elaborate a bit by asking, "Is it possible to /certainly/ stop ...
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2answers
92 views

Protecting account ssh keys from root

How can users ssh private keys be protected from root stealing and attempting to brute force them? I cannot use selinux as the vendor will not support the app when it's in use? Thanks
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1answer
106 views

Hacked debian server alternative boot

The server of a customer has been hacked last night. It is a standard debian distribution with mysql, apache and ssh for remote access. The way it has been hacked is very peculiar. The standard URL ...