HackDig : Dig high-quality web security articles for hackers

Linux ASLR mmap weakness: Reducing entropy by half

2015-04-21 21:30
A bug in Linux ASLR implementation has been found. The issue is that the mmap base address for processes is not properly randomized on some architectures due to an improper bit-mask manipulation. Affected systems have reduced the mmap area entropy of the processes by half.


The number of possible locations are reduced by 50%, which for example will reduce the cost of brute force attacks.


PowerPC, Sparc64 and ARM have 18 bits of entropy. Non-vulnerable systems have 262144 (2^18) different places to locate the mmap area. On vulnerable systems, this value is reduced to 131072 (2^17).



Advisory details at:
http://hmarco.org/bugs/linux-ASLR-reducing-mmap-by-half.html


--
Hector Marco-Gisbert @ http://hmarco.org/
Cyber Security Researcher @ http://cybersecurity.upv.es
Universitat Politècnica de València (Spain)

_______________________________________________
Sent through the Full Disclosure mailing list
https://nmap.org/mailman/listinfo/fulldisclosure
Web Archives & RSS: http://seclists.org/fulldisclosure/


Source: 07/rpA/5102/erusolcsidlluf/gro.stsilces

Read:3126 | Comments:0 | Tags:No Tag

“Linux ASLR mmap weakness: Reducing entropy by half”0 Comments

Submit A Comment

Name:

Email:

Blog :

Verification Code:

Tools

Tag Cloud