arc insecure temporary file creation

Advisory Content :

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arc insecure temporary file creation

Vendor: http://arc.sourceforge.net/
Advisory: http://www.zataz.net/adviso/arc-09052005.txt
Vendor informed: yes
Exploit available: yes
Impact : low
Exploitation : low

#########################################################

The vulnerability is caused due to temporary file being created insecurely.
The temporary file used for archive creation could be read by untrusted
users.

Secunia has reported that D1g1t4lLeech has discovered this bug the
2005-09-16.

ZATAZ Audit has discovered this bug the 2005-09-05

D1g1t4lLeech you are a true Leecher ;)

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Versions:
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arc <= 5.21j

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Solution:
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No solutions

#########
Timeline:
#########

Discovered : 2005-09-05
Vendor notified : no time to report (Leech powa)
Vendor response : no reponse
Vendor fix : no patch
Vendor Sec report (vendor-sec (at) lst (dot) de [email concealed]) :
Disclosure : 2005-09-19

#####################
Technical details :
#####################

Vulnerable code :
-----------------

In arc.c :

210 /* see where temp files go */
211 #if !_MTS
212 arctemp = calloc(1, STRLEN);
213 if (!(arctemp2 = envfind("ARCTEMP")))
214 arctemp2 = envfind("TMPDIR");
215 if (arctemp2) {
216 strcpy(arctemp, arctemp2);
217 n = strlen(arctemp);
218 if (arctemp[n - 1] != CUTOFF)
219 arctemp[n] = CUTOFF;
220 }
221 #if UNIX
222 else strcpy(arctemp, "/tmp/");
223 #endif
224 #if !MSDOS
225 {
226 static char tempname[] = "AXXXXXX";
227 strcat(arctemp, mktemp(tempname));
228 }
229 #else
230 strcat(arctemp, "$ARCTEMP");
231 #endif
232 #else
233 guinfo("SHFSEP ", gotinf);
234 sepchr[0] = gotinf[0];
235 guinfo("SCRFCHAR", gotinf);
236 tmpchr[0] = gotinf[0];
237 arctemp = "-$$$";
238 arctemp[0] = tmpchr[0];
239 #endif
240 arctemp2 = NULL;
241
242 #if !UNIX
243 /* avoid any case problems with arguments */
244
245 for (n = 1; n < num; n++) /* for each argument */
246 upper(arg[n]); /* convert it to uppercase */
247 #else
248 /* avoid case problems with command options */
249 upper(arg[1]); /* convert to uppercase */
250 #endif
251
252 /* create archive names, supplying defaults */
253 #if UNIX
254 if (!stat(arg[2],&sbuf)) {
255 if ((sbuf.st_mode & S_IFMT) == S_IFDIR)
256 makefnam(arg[2],".arc",arcname);
257 else
258 strcpy(arcname,arg[2]);
259 } else
260 makefnam(arg[2],".arc",arcname);
261 #else
262 makefnam(arg[2], ".ARC", arcname);
263 #endif

Take a look on a the right off temporary files in /tmp :

-rw-r--r-- 1 root root 1564 Sep 5 10:28 A3C6Zs4.arc

The file should not be world readable.

The same problem for marc.c

#########
Related :
#########

Bug report :
CVE :

#####################
Credits :
#####################

Eric Romang (eromang (at) zataz (dot) net [email concealed] - ZATAZ Audit)
Thxs to Gentoo Security Team. (Taviso, jaervosz, solar, Koon, etc.)

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arc insecure temporary file creation