linux-kernel - Re: SHMEM question

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Tue, 27 Oct 2009 14:25:49 +0100
From:	Gabor Gombas <gombasg@...aki.hu>
To:	Gene Heskett <gene.heskett@...izon.net>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: SHMEM question

On Mon, Oct 26, 2009 at 11:59:04AM -0400, Gene Heskett wrote:

> On looking at it:
> [root@...ote Download]# ls -l /dev/shm
> total 28
> -rw-r----- 1 root root     4096 2009-10-25 12:09 mono.10594
> -r-------- 1 root root 67108904 2009-10-24 00:28 pulse-shm-3880918577
> -rw-rw-rw- 1 root root       16 2009-10-24 01:17 sem.ADBE_ReadPrefs_root
> -rw-rw-rw- 1 root root       16 2009-10-24 01:17 sem.ADBE_REL_root
> -rw-rw-rw- 1 root root       16 2009-10-24 01:17 sem.ADBE_WritePrefs_root
> 
> On grepping for SHM in the .config, I find SHMEM set to y, but about an hours 
> worth of wandering around in a 'make xconfig' has failed to actually find it.

No wonder, it has nothing to do with the kernel. glibc uses /dev/shm to
implement POSIX shared memory, see shm_overview(7).

> That pulse-shm-3880918577 file at over 67 megabytes is all $00 till $04000000 
> into it, then there is 6 non-zero bytes and the rest is back to all balls.

If it bothers you then do not use pulseaudio.

> Is this some indicator of a new rootkit or WTF?

Not neccessarily. However since most people never look into /dev/shm,
it's not a bad place to hide data. But it will go away at reboot, so
it's not that useful for a rootkit.

Gabor

-- 
     ---------------------------------------------------------
     MTA SZTAKI Computer and Automation Research Institute
                Hungarian Academy of Sciences
     ---------------------------------------------------------
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/