blob: 2faf51f45563628d1574ef89bceddf03aa23f46d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
custodian-enqueue
-----------------
We open named files from the user to parse tests. The configuration file(s)
are currently opened by root, via /etc/service/custodian-enqueue. This should
be changed to run as a lower-privileged user.
custodian-dequeue
-----------------
Two tests pass arguments from the configuration file to the shell:
ping
http/https
The hostname used to ping, and the URL for web-tests, are both passed directly to the shell assuming they match the following regular expression:
^([^\s]+)\s+
So the following configuration file potentially allows a command to be executed by our worker:
$(/home/steve/hg/custodian/exploit.sh) must ping otherwise "Owned".
http://$(/tmp/exploit.sh)/ must run http with status 200 otherwise "Owned".
Given that anybody who can talk to the beanstalkd server can submit JSON-encoded-jobs we cannot rely on catching this solely in the parser.
For the moment we've solved the case of the ping-exploitation, because the
valid hostnames passed there are [a-z0-9.-]. We've not yet sanitized URLs
because that is a harder job.
In the case of the ping-test we've done both levels of testing:
* Test the hostname is valid priorer to executing the shell.
* Ensure the hostname is valid before adding the job to the queue.
General
-------
We decode arbitrary JSON from the queue. We should sign it, or validate it to will prevent trojan malformed
JSON from being added.
At the moment we ensure that the job-body we retrieve looks JSON-like, and decodes to a non-empty hash.
Problem: We cannot sign the body without giving away our key details.
Solution: Read /etc/custodian/salt, and store the checksum of all keys + values with that salt?
TODO
----
Anything else? DoS attacks?
Steve
--
|
