Securing Linux systems and applications; understanding Linux security features.

learn more… | top users | synonyms

3
votes
1answer
27 views

My sendmail started sending spam; what is causing it to do so?

Today my sendmail service started sending e-mail to various addresses. /var/spool/mail: From MAILER-DAEMON@noxcommunity.com Fri Jan 30 22:15:30 2015 Return-Path: ...
1
vote
2answers
38 views

How should I deal with adware in chrome on ubuntu?

I use chrome (but also have firefox) on ubuntu 14.04 32-bit. Recently I started getting popups from 'softwareupdaterlp.com'. I had the sense to realize it was not legitimate and I didn't click install ...
5
votes
1answer
70 views

Is Java vulnerable to glibc GHOST Vulnerability in Linux?

I see on our RedHat Linux platform that "java" process has dependency over glibc library: [root@hpproliant1 ~]# ldd /usr/bin/java linux-gate.so.1 => (0xffffe000) libpthread.so.0 => ...
7
votes
1answer
190 views

Bootstrapping an EC2 Spot Instance

I'm considering using EC2 Spot Instances in an automated fashion (ie create a script that will request EC2 Spot Instances that will run unattended). For this specific use case, I'm happy to lock down ...
1
vote
1answer
70 views

Read SSL Certs with user process

I am running my own server, on which I have different services (Nginx etc.). All these (internet) services are / should be secured with SSL (offcialy signed). The key files / certificates are located ...
0
votes
0answers
18 views

Monitor system calls performance counters [closed]

I am working on a project and I would like to obtain the performance counters(cache TLB, etc) values of a system call(eg: read()) before and after the execution of a file. I tried doing this using ...
0
votes
2answers
110 views

Tails OS for Android and PC?

Can I use Tails OS on a USB-stick on both an Android tablet and a PC, or do I have to have two different versions? Would I have to go into the BIOS to make this work?
0
votes
0answers
42 views

OpenSSH downgrade attack

I have tried to implement a downgrade attack against the SSH protocol as the first steps (encryption protocols exchange) are not signed, as per RFC4253. The idea is to intercept (mitm) these steps and ...
1
vote
1answer
115 views

Securing a VPS network with a VPN and a DMZ

I've got several VPS boxes (Digital Ocean boxes w/Ubuntu) that I would like to lock down from the outside world. I want to have several private boxes (web servers, db servers, puppet/master boxes ...
16
votes
3answers
1k views

Why doesn't Linux randomize the address of the executable code segment?

I've recently been learning about how ASLR (address space randomization) works on Linux. At least on Fedora and Red Hat Enterprise Linux, there are two kinds of executable programs: Position ...
0
votes
1answer
43 views

Bogus HostName Causing Suspicion of Man In The Middle

I have servers on a LAN reporting my laptop with a bogus hostname. This is making me suspect a man in the middle attack. Here are some details: From an Ubuntu Linux 14.04 laptop, I logged into an ...
0
votes
0answers
75 views

Is there any method to prevent/trace ddos attack?

I have a debian linux server which run a few online game services. I have some competitors in this area and i think one of them is behind the ddos attacks. I have full access to the router, so I set ...
3
votes
2answers
3k views

Best method to sandbox X applications in ubuntu

What's the best way to sandbox an X application like firefox or thunderbird in ubuntu (going into the direction of what qubes os does, but only for single applications)? I know there are many ...
2
votes
2answers
53 views

Linux Repo Security

Can a registered 3rd party repo spoof critical packages (e.g libc6) and have them installed on apt 'upgrade' operations? What are the best ways (configuration) to help manage 3rd party repos to ...
1
vote
2answers
237 views

Malware getting root access via “sudo” and “sudo -s”

Actually, I'd like to ask 3 questions. But since they are very related, I'll ask them all here. I use Ubuntu 12.04.4. Situation 1: I use Terminator, in one of its terminals I launch sudo iotop ...
3
votes
1answer
131 views

What is a secure mechanism for wireless communication between Android and Ubuntu?

I have come across a few Android apps that provide various features for communicating with a desktop machine (sending text or typing in one direction or another, controlling the desktop pointer with ...
3
votes
0answers
55 views

Is there a way to check for “hollow” processes, or malware hidden within “normal” processes

I recently came across an article on the The Verge, which centers around the concept of commercial malware production and how it's used around the world. The article introduced me to a number of ...
2
votes
1answer
40 views

How does the Samba misconfigured '/etc/passwd' file security bypass vulnerability work?

I just found this vulnerability on http://www.securityfocus.com/bid/36363/references, which affects several samba server 3.0.xx. Can anyone explain more about this vulnerability? How this bypass ...
0
votes
1answer
136 views

Log information for SIEM auditing in Linux

How can I know what all types of events generated by Linux. I can get this from the logs, but reading logs and noting ID's is very time consuming. All events might not be triggered. I need this ...
0
votes
1answer
34 views

Gnome-keyring iteration count location

I know that Gnome-keyring hashes master password between 1000 and 2000 times. It picks random number. I would like to ask where does it save this number, what is the location of that file? As far as I ...
1
vote
2answers
74 views

About SHA1 in default Disk Encryption in Linux

Link to the Thread: Recommended options for LUKS (cryptsetup) I wonder what's the exact difference between SHA1 and SHA512. I know that SHA512 has a longer key but I've read that it doesn't matter ...
5
votes
2answers
487 views

Security of Linux Full Disk Encryption (Ubuntu / Mint) -insecure?

I'm wondering, why is Ubuntu and Mint using SHA1 for Full Disk Encryption? I heard several times that SHA1 shouldn't be used anymore because it is weak and it could be cracked. Could you guys ...
0
votes
0answers
27 views

Bruteforce with Hydra [duplicate]

I'm trying to use a Hydra script in the following scenario on localhost and Linux: After web form login, my app redirects to another page with header(Location: internalpage.php) I use this syntax ...
77
votes
3answers
12k views

Is a rand from /dev/urandom secure for a login key?

Lets say I want to create a cookie for a user. Would simply generating a 1024 bit string by using /dev/urandom, and checking if it already exists (looping until I get a unique one) suffice? Or should ...
0
votes
0answers
46 views

Is there any security risk with adding a **root's** public key to the local user's authorized_keys (so root to login as a user non-interactively?)

Background: I want to try unprivileged lxc containers a try on my small web server (hosting 2-4 users). Since the server is shared among friends, we decided to separate our services from the machine ...
2
votes
1answer
54 views

Upload a file into directory with public write access

I know it is not right to set a permission for the folder as 777, but if it is done so will it be possible to upload a file into that directory without ftp access ? Here is what I mean Lets say the ...
3
votes
1answer
48 views

Key generation: Differences between GnuPG classic, stable, modern?

I plan to create a 4096 bit RSA&RSA key pair: gpg --gen-key --personal-digest-preferences SHA512 --cert-digest-algo SHA512 Is there any difference in generated key quality between versions 1.4 ...
0
votes
0answers
18 views

PHP file Upload & execution Prevention [migrated]

I am security administrator for a shared Linux web hosting. I have done my level best to secure the server in many ways within the possible limitation. Means, As it is shared hosting, there will be ...
2
votes
1answer
217 views

Current industry standard key management solution for web app on linux host

The scenario: Data is sent to an application server and you want to selectively encrypt some data before sending it to a DB server for storage. All servers run some linux distro. This is a relatively ...
2
votes
2answers
77 views

Firewall egress filtering / quick whitelisting

Suppose your Aunt or Uncle is easily fooled by phishing attempts and their computer has multiple root kits and key loggers running. Assume their computing habits will never change. Looking at his ...
14
votes
6answers
2k views

Convenient cross-platform help on checking secure hashes like SHA-256

It is often helpful to be able to obtain a good cryptographic checksum of a file, e.g. the SHA-256 hash. This can be used to verify file integrity, so long as you have a reliable source for the hash. ...
0
votes
2answers
67 views

Safe to use setuid with absolutely no input?

I have a shell script which syncs some files from a remote source and I have a pretty typical HTTP server set-up. There is a user who owns the files served by the HTTP server and a user which runs the ...
2
votes
5answers
139 views

Why can't just any program use his own file-system-access-system?

This may sound stupid for everyone who knows more than me about the UNIX-System and security in software: Imagine you have a program trying to cause harm by deleting files. You just do something like ...
3
votes
2answers
58 views

How to securely install software on Ubuntu?

How to install a software like Sublime Text on Ubuntu 14.04 LTS and mitigate against a MITM attack? There is a PPA available, but the PPA must be added manually. I don't see any PGP keys or MD5 ...
7
votes
2answers
155 views

List all files with only arbitrary file path read, but no directory listing nor sudo

I have found a path traversal vulnerability that allows me to read any path on the server that does not require sudo. To fully exploit this, I would like to know which files exist in each directory ...
-1
votes
2answers
3k views

Hydra https-form-post

I have never experimented much with online password crackers. I attempted to use Hydra today on this website www.athena2.harker.org and I keep getting false positives. This is what I have done so ...
0
votes
2answers
78 views

Running tails on a corporate computer

Is it safe to run TAILS on a corporate computer? I mean a corporate computer that has hardware cryptography and probably some backdoors; and, by safe, I mean that nobody will be able to recover what ...
0
votes
0answers
68 views

Protecting against bad USB in ubuntu

I am referring to this thread: How to prevent BadUSB attacks on linux desktop Since i want to install ubunto onto a possible infected usbDrive using a live DVD and the installation manager i was ...
4
votes
1answer
5k views

what does it mean to be setuid root?

I am reading Tanenbaum's Modern Operating Systems 3e. He says "Suppose that the program being attacked [with malicious code] is SETUID root in UNIX (or has Administrator power in Windows). The ...
1
vote
2answers
229 views

Debian encryption is as safe as Truecrypt. Is this correct?

When I try to install latest debian to my pc, the wizard ask me to input a password to do FDE(full disk encryption). My questions are: What algorithm does Debian use? (Truecrypt = AES) Can I change ...
0
votes
1answer
18 views

SELinux ignoring /etc/sysconfig/selinux directive

I'm running SELinux on CentOS 6.5. In /etc/sysconfig/selinux I have set SELINUX=permissive. But everytime the system starts, sudo getenforce shows SELinux as Enforcing. What could be causing it to go ...
-1
votes
1answer
115 views

ARP: Forwarding or dropping with IPTABLES

So, I ve been trying to ARP Poison my home computer and router (Intended to learn and discover the networks bahaviour). And with success. The whole time I ve been using: with ...
-1
votes
2answers
67 views

Is openVZ patched against all exploits for its current kernel version?

I am looking for a container vitalization software that will allow me to create containers that will house specific software/jobs/tasks which I can start stop at will (and bind to interface aliases). ...
2
votes
2answers
93 views

LUKS nuke efficiency

I am wondering about LUKS nuke patch efficiency. In fact, I think I don't really understand it. From what I know of LUKS, a passphrase is used to encrypt a random key (the master key), which is used ...
0
votes
2answers
594 views

Exploit failed [unreachable]: Rex::ConnectionTimeout The connection timed out(remote host ip)

I keep getting this when I start to exploit, trying to exploit my xp machine but this keeps happening, I can not find the fix anywhere, I don't believe I am the only one getting this.. I am a ...
0
votes
0answers
62 views

Secure password transfer from stdout to another window

I am currently trying to build a little, secure password manager. As of now, I've implemented the encryption. Each website has its own file and each file has a number of fields (Most commonly username ...
1
vote
3answers
257 views

Cracking passwords after a pattern with John

So I am trying to find out how easy it is to crack a password using some great Linux tools. We all know about John as a password cracker and how great it is. But how about specifying a pattern. ...
1
vote
1answer
47 views

Security implication of non-free drivers

I was wondering what the security implications are of using non-free drivers on a linux laptop. Especially for graphics and wifi.
17
votes
3answers
1k views

Linux-based Turla trojan

There are several articles describing the newly discovered Linux-based Turla trojan. But basically, all these articles repeat the same, very limited, information. Can anybody provide more details, ...
9
votes
1answer
71 views

Security measures and anti-virus on server to mitigate acting as a propagation vector

We have a web application for which I've been asked to add the ability to let users upload documents that will then be visible and downloadable by other users. Those documents will typically be images ...