Pcapy (Sniffing) on WiFi2006-12-09

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I like to develop on my (Windows) laptop... I also like to develop from the comfort of my sweet Corda-Roy bean bag chair, which means I'll be connected via WiFi. Unfortunately sniffing via Ethereal or CORE's Pcapy library is not possible in this situation. I came up with a convenient 2-step solution to my woe that perhaps others will find useful.

First, snag yourself an Ethernet Loopback Jack and plug it in. This will trick your NIC into thinking it's actually plugged into a network. Next, create a network bridge and add the LAN adapter followed by the WiFi adapter. The network bridge shows up as a new interface that you can sniff on!

***** UPDATE *****
tagetora was kind enough to write me and suggest trying to bridge with a loop back device to avoid the additional hardware. I'm pleased to report that it works like a charm. For instructions on how to create a loop back device see: http://support.microsoft.com/kb/839013.

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Owning Computer Associates BrightStor through Mailslots2006-10-05

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Recall from blog/2006-07-11 and TSRT-06-02 that any code relying on the implicit message size limitation of Second-class Mailslots could be exposing a vulnerability. I mentioned that the rare usage of Mailslots will severely mitigate the impact of this new "class" of vulnerability. The fact that no Mailslot bugs have emerged since the initial disclosure is evidence that my assumption was true.

The one 3rd party exposure I have personally come across was just disclosed today: CA BrightStor Discovery Service Mailslot Buffer Overflow Vulnerability. The exposed Mailslot name is 'CheyenneDS' and a no explicit MaxMessageSize is supplied in the call to CreateMailslot, an attacker can cause an exploitable stack-based buffer overflow. Here is the creation of the Mailslot:

casdscsvc.exe -> Asbrdcst.dll
 20C14E8C push 0                ; lpSecurityAttributes
 20C14E8E push 0                ; lReadTimeout
 20C14E90 push 0                ; nMaxMessageSize
 20C14E92 push offset Name      ; "\\\\.\\mailslot\\CheyenneDS"
 20C14E97 stosb
 20C14E98 call ds:CreateMailslotA
 20C14EA1 mov mailslot_handle, eax

Later the mailslot handle is read from into a 4k buffer. The read data is also passed to a routine which calls vsprintf into a 1k buffer.

casdscsvc.exe -> Asbrdcst.dll
 20C15024 mov eax, mailslot_handle
 20C15029 lea edx, [esp+1044h+Buffer_4k]
 20C1502D push ecx                        ; nNumberOfBytesToRead
 20C1502E push edx                        ; lpBuffer
 20C1502F push eax                        ; hFile
 20C15030 call edi ; ReadFile
 20C15032 test eax, eax
 20C15034 jz  short read_failed
 20C15036 lea ecx, [esp+3Dh]
 20C1503A push ecx                        ; char
 20C1503B push offset str_ReadmailslotS   ; "ReadMailSlot: %s\n"
 20C15040 call not_interesting_call_to_vsnprtinf
 20C15045 add esp, 8
 20C15048 lea edx, [esp+3Dh]
 20C1504C push edx                        ; va_list
 20C1504D push offset str_ReadmailslotS_0 ; "ReadMailSlot: %s"
 20C15052 push 0                          ; for_debug_log
 20C15054 call vsprintf_into_1024_stack_buf_and_debug_log

One would imagine that at least one other instance of a Mailslot handling bug must exist elsewhere. Anyone?

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eEye Binary Diffing Suite (EBDS)2006-08-10

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Just wanted to drop a quick note regarding eEye's recently released bin-diffing tool:


It's definitely badass and it definitely took a lot of work to put together. It's also open source and a large portion of it is written in Python, so lots of new toys for me to play with. I'm particularly interested in their embedded graph view. They used QT vs. WX (which is what I'm used to), but I'm sure portions can be re-used.

On a separate but somewhat similar note. I was originally going to store PIDA output to MySQL and forget now why I decided against that. However, in light of the virtual memory consumption issues I will be moving to that backend (with dynamic queries / "free()'s"). Not to worry for anyone (if there is anyone) who has built scripts on top of PaiMei already; the interfaces will not change. I think I've mentioned it before, but I'll use the schema from SABRE in efforts of gaining widespread acceptance and "standarization". All in due time ... when I find the time.

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